json、javaBean、xml互轉的幾種工具介紹

時間 2019-12-08

標籤 json javabean xml 幾種工具介紹欄目 JavaScript 简体版

原文原文鏈接

json、javaBean、xml互轉的幾種工具介紹

轉載至:http://blog.csdn.net/sdyy321/article/details/7024236java

工做中常常要用到Json、JavaBean、Xml之間的相互轉換，用到了不少種方式，這裏作下總結，以供參考。git

如今主流的轉換工具備json-lib、jackson、fastjson等，我爲你們一一作簡單介紹，主要仍是以代碼形式貼出如何簡單應用這些工具的，更多高級功能還需你們深刻研究。github

首先是json-lib，算是很早的轉換工具了，用的人不少，說實在如今徹底不適合了，缺點比較多，依賴的第三方實在是比較多，效率低下，API也比較繁瑣，說他純粹是由於之前的老項目不少人都用到它。不廢話，開始上代碼。json

須要的maven依賴：數組

    <!-- for json-lib -->
    <dependency>  
        <groupId>net.sf.json-lib</groupId>  
        <artifactId>json-lib</artifactId>  
        <version>2.4</version>  
        <classifier>jdk15</classifier>  
    </dependency>
    <dependency>
        <groupId>xom</groupId>
        <artifactId>xom</artifactId>
        <version>1.1</version>
    </dependency> 
    <dependency>
        <groupId>xalan</groupId>
        <artifactId>xalan</artifactId>
        <version>2.7.1</version>
    </dependency>

使用json-lib實現多種轉換app

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import javax.swing.text.Document;
import net.sf.ezmorph.Morpher;
import net.sf.ezmorph.MorpherRegistry;
import net.sf.ezmorph.bean.BeanMorpher;
import net.sf.ezmorph.object.DateMorpher;
import net.sf.json.JSON;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JSONSerializer;
import net.sf.json.JsonConfig;
import net.sf.json.processors.JsonValueProcessor;
import net.sf.json.util.CycleDetectionStrategy;
import net.sf.json.util.JSONUtils;
import net.sf.json.xml.XMLSerializer;

/**
 * json-lib utils
 * @author magic_yy
 * @see json-lib.sourceforge.net/
 * @see https://github.com/aalmiray/Json-lib
 *
 */
public class JsonLibUtils {
    
    public static JsonConfig config = new JsonConfig();
    
    static{
        config.setCycleDetectionStrategy(CycleDetectionStrategy.LENIENT);//忽略循環，避免死循環
        config.registerJsonValueProcessor(Date.class, new JsonValueProcessor() {//處理Date日期轉換
            @Override
            public Object processObjectValue(String arg0, Object arg1, JsonConfig arg2) {
                 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                    Date d=(Date) arg1;
                    return sdf.format(d);
            }
            @Override
            public Object processArrayValue(Object arg0, JsonConfig arg1) {
                return null;
            }
        });
    }
    
    /** 
     * java object convert to json string
     */  
    public static String pojo2json(Object obj){
        return JSONObject.fromObject(obj,config).toString();//能夠用toString(1)來實現格式化，便於閱讀  
    }  
      
    /** 
     * array、map、Javabean convert to json string
     */  
    public static String object2json(Object obj){  
        return JSONSerializer.toJSON(obj).toString();  
    }  
      
    /** 
     * xml string convert to json string
     */  
    public static String xml2json(String xmlString){  
        XMLSerializer xmlSerializer = new XMLSerializer();  
        JSON json = xmlSerializer.read(xmlString);  
        return json.toString();  
    }  
      
    /** 
     * xml document convert to json string
     */  
    public static String xml2json(Document xmlDocument){  
        return xml2json(xmlDocument.toString());  
    }  
      
    /** 
     * json string convert to javaBean
     * @param <T>
     */  
    @SuppressWarnings("unchecked")
    public static <T> T json2pojo(String jsonStr,Class<T> clazz){  
        JSONObject jsonObj = JSONObject.fromObject(jsonStr);  
        T obj = (T) JSONObject.toBean(jsonObj, clazz);  
        return obj;  
    }
    
    /**
     * json string convert to map
     */
    public static Map<String,Object> json2map(String jsonStr){
        JSONObject jsonObj = JSONObject.fromObject(jsonStr);
        Map<String,Object> result = (Map<String, Object>) JSONObject.toBean(jsonObj, Map.class);
        return result;
    }
    
    /**
     * json string convert to map with javaBean
     */
    public static <T> Map<String,T> json2map(String jsonStr,Class<T> clazz){
        JSONObject jsonObj = JSONObject.fromObject(jsonStr);
        Map<String,T> map = new HashMap<String, T>();
        Map<String,T> result = (Map<String, T>) JSONObject.toBean(jsonObj, Map.class, map);
        MorpherRegistry morpherRegistry = JSONUtils.getMorpherRegistry();
        Morpher dynaMorpher = new BeanMorpher(clazz,morpherRegistry);
        morpherRegistry.registerMorpher(dynaMorpher);
        morpherRegistry.registerMorpher(new DateMorpher(new String[]{ "yyyy-MM-dd HH:mm:ss" }));
        for (Entry<String,T> entry : result.entrySet()) {
            map.put(entry.getKey(), (T)morpherRegistry.morph(clazz, entry.getValue()));
        }
        return map;
    }
      
    /** 
     * json string convert to array
     */  
    public static Object[] json2arrays(String jsonString) {  
        JSONArray jsonArray = (JSONArray) JSONSerializer.toJSON(jsonString);
//        JSONArray jsonArray = JSONArray.fromObject(jsonString);  
        JsonConfig jsonConfig = new JsonConfig();
        jsonConfig.setArrayMode(JsonConfig.MODE_OBJECT_ARRAY);
        Object[] objArray = (Object[]) JSONSerializer.toJava(jsonArray,jsonConfig);
        return objArray;
    }  
      
    /** 
     * json string convert to list
     * @param <T>
     */  
    @SuppressWarnings({ "unchecked", "deprecation" })
    public static <T> List<T> json2list(String jsonString, Class<T> pojoClass){  
        JSONArray jsonArray = JSONArray.fromObject(jsonString);  
        return JSONArray.toList(jsonArray, pojoClass);
    }  
      
    /** 
     * object convert to xml string
     */  
    public static String obj2xml(Object obj){  
        XMLSerializer xmlSerializer = new XMLSerializer();  
        return xmlSerializer.write(JSONSerializer.toJSON(obj));  
    }  
      
    /** 
     * json string convert to xml string
     */  
    public static String json2xml(String jsonString){  
        XMLSerializer xmlSerializer = new XMLSerializer();  
        xmlSerializer.setTypeHintsEnabled(true);//是否保留元素類型標識，默認true
        xmlSerializer.setElementName("e");//設置元素標籤，默認e
        xmlSerializer.setArrayName("a");//設置數組標籤，默認a
        xmlSerializer.setObjectName("o");//設置對象標籤，默認o
        return xmlSerializer.write(JSONSerializer.toJSON(jsonString));  
    }
    
}

都是些比較常見的轉換，寫的不是很全，基本夠用了，測試代碼以下：maven

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import net.sf.ezmorph.test.ArrayAssertions;
import org.junit.Assert;
import org.junit.Test;

public class JsonLibUtilsTest {

    @Test
    public void pojo2json_test(){
        User user = new User(1, "張三");
        String json = JsonLibUtils.pojo2json(user);
        Assert.assertEquals("{\"id\":1,\"name\":\"張三\"}", json);
    }
    
    @Test
    public void object2json_test(){
        int[] intArray = new int[]{1,4,5};
        String json = JsonLibUtils.object2json(intArray);
        Assert.assertEquals("[1,4,5]", json);
        User user1 = new User(1,"張三");
        User user2 = new User(2,"李四");
        User[] userArray = new User[]{user1,user2};
        String json2 = JsonLibUtils.object2json(userArray);
        Assert.assertEquals("[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]", json2);
        List<User> userList = new ArrayList<>();
        userList.add(user1);
        userList.add(user2);
        String json3 = JsonLibUtils.object2json(userList);
        Assert.assertEquals("[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]", json3);
        //這裏的map的key必須爲String類型
        Map<String,Object> map = new HashMap<>();
        map.put("id", 1);
        map.put("name", "張三");
        String json4 = JsonLibUtils.object2json(map);
        Assert.assertEquals("{\"id\":1,\"name\":\"張三\"}", json4);
        Map<String,User> map2 = new HashMap<>();
        map2.put("user1", user1);
        map2.put("user2", user2);
        String json5 = JsonLibUtils.object2json(map2);
        Assert.assertEquals("{\"user2\":{\"id\":2,\"name\":\"李四\"},\"user1\":{\"id\":1,\"name\":\"張三\"}}", json5);
    }
    
    @Test
    public void xml2json_test(){
        String xml1 = "<User><id>1</id><name>張三</name></User>";
        String json = JsonLibUtils.xml2json(xml1);
        Assert.assertEquals("{\"id\":\"1\",\"name\":\"張三\"}", json);
        String xml2 = "<Response><CustID>1300000428</CustID><Items><Item><Sku_ProductNo>sku_0004</Sku_ProductNo></Item><Item><Sku_ProductNo>0005</Sku_ProductNo></Item></Items></Response>";
        String json2 = JsonLibUtils.xml2json(xml2);
        //處理數組時expected是處理結果，但不是咱們想要的格式
        String expected = "{\"CustID\":\"1300000428\",\"Items\":[{\"Sku_ProductNo\":\"sku_0004\"},{\"Sku_ProductNo\":\"0005\"}]}";
        Assert.assertEquals(expected, json2);
        //實際上咱們想要的是expected2這種格式,因此用json-lib來實現含有數組的xml to json是不行的
        String expected2 = "{\"CustID\":\"1300000428\",\"Items\":{\"Item\":[{\"Sku_ProductNo\":\"sku_0004\"},{\"Sku_ProductNo\":\"0005\"}]}}";
        Assert.assertEquals(expected2, json2);
    }
    
    @Test
    public void json2arrays_test(){
        String json = "[\"張三\",\"李四\"]";
        Object[] array = JsonLibUtils.json2arrays(json);
        Object[] expected = new Object[] { "張三", "李四" };
        ArrayAssertions.assertEquals(expected, array);                                                                                            
        //沒法將JSON字符串轉換爲對象數組
        String json2 = "[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]";
        Object[] array2 = JsonLibUtils.json2arrays(json2);
        User user1 = new User(1,"張三");
        User user2 = new User(2,"李四");
        Object[] expected2 = new Object[] { user1, user2 };
        ArrayAssertions.assertEquals(expected2, array2);
    }
    
    @Test
    public void json2list_test(){
        String json = "[\"張三\",\"李四\"]";
        List<String> list = JsonLibUtils.json2list(json, String.class);
        Assert.assertTrue(list.size()==2&&list.get(0).equals("張三")&&list.get(1).equals("李四"));
        String json2 = "[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]";
        List<User> list2 = JsonLibUtils.json2list(json2, User.class);
        Assert.assertTrue(list2.size()==2&&list2.get(0).getId()==1&&list2.get(1).getId()==2);
    }
    
    @Test
    public void json2pojo_test(){
        String json = "{\"id\":1,\"name\":\"張三\"}";
        User user = (User) JsonLibUtils.json2pojo(json, User.class);
        Assert.assertEquals(json, user.toString());
    }
    
    @Test
    public void json2map_test(){
        String json = "{\"id\":1,\"name\":\"張三\"}";
        Map map = JsonLibUtils.json2map(json);
        int id = Integer.parseInt(map.get("id").toString());
        String name = map.get("name").toString();
        System.out.println(name);
        Assert.assertTrue(id==1&&name.equals("張三"));
        String json2 = "{\"user2\":{\"id\":2,\"name\":\"李四\"},\"user1\":{\"id\":1,\"name\":\"張三\"}}";
        Map map2 = JsonLibUtils.json2map(json2, User.class);
        System.out.println(map2);
    }
    
    @Test
    public void json2xml_test(){
        String json = "{\"id\":1,\"name\":\"張三\"}";
        String xml = JsonLibUtils.json2xml(json);
        Assert.assertEquals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n<o><id type=\"number\">1</id><name type=\"string\">張三</name></o>\r\n", xml);
        System.out.println(xml);
        String json2 = "[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]";
        String xml2 = JsonLibUtils.json2xml(json2);
        System.out.println(xml2);
        Assert.assertEquals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n<a><e class=\"object\"><id type=\"number\">1</id><name type=\"string\">張三</name></e><e class=\"object\"><id type=\"number\">2</id><name type=\"string\">李四</name></e></a>\r\n", xml2);
    }
    
    public static class User{
        private int id;
        private String name;
        
        public User() {
        }
        public User(int id, String name) {
            this.id = id;
            this.name = name;
        }
        @Override
        public String toString() {
            return "{\"id\":"+id+",\"name\":\""+name+"\"}";
        }
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
    }
}

json-lib在XML轉換爲JSON在有數組的狀況下會有問題，還有在JSON轉換爲XML時都會有元素標識如<o><a><e>等，在通常狀況下咱們可能都不須要，暫時還不知道如何過濾這些元素名稱。ide

由於json-lib的種種缺點，基本中止了更新，也不支持註解轉換，後來便有了jackson流行起來，它比json-lib的轉換效率要高不少，依賴不多，社區也比較活躍，它分爲3個部分：工具

Streaming (docs) ("jackson-core") defines low-level streaming API, and includes JSON-specific implementations
Annotations (docs) ("jackson-annotations") contains standard Jackson annotations
Databind (docs) ("jackson-databind") implements data-binding (and object serialization) support on streaming package; it depends both on streaming and annotations packages

咱們依舊開始上代碼，首先是它的依賴：測試

      <!-- for jackson -->
    <dependency>
          <groupId>com.fasterxml.jackson.dataformat</groupId>
          <artifactId>jackson-dataformat-xml</artifactId>
          <version>2.1.3</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.1.3</version>
        <type>java-source</type>
        <scope>compile</scope>
    </dependency>

這裏我要說下，有不少基於jackson的工具，你們能夠按照本身的實際需求來需找對應的依賴，我這裏爲了方便轉換xml因此用了dataformat-xml和databind

使用jackson實現多種轉換：

package cn.yangyong.fodder.util;

import java.io.StringWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;

/**
 * jsonson utils
 * @see http://jackson.codehaus.org/
 * @see https://github.com/FasterXML/jackson
 * @see http://wiki.fasterxml.com/JacksonHome
 * @author magic_yy
 *
 */
public class JacksonUtils {
    
    private static ObjectMapper objectMapper = new ObjectMapper();
    private static XmlMapper xmlMapper = new XmlMapper();
    
    /**
     * javaBean,list,array convert to json string
     */
    public static String obj2json(Object obj) throws Exception{
        return objectMapper.writeValueAsString(obj);
    }
    
    /**
     * json string convert to javaBean
     */
    public static <T> T json2pojo(String jsonStr,Class<T> clazz) throws Exception{
        return objectMapper.readValue(jsonStr, clazz);
    }
    
    /**
     * json string convert to map
     */
    public static <T> Map<String,Object> json2map(String jsonStr)throws Exception{
        return objectMapper.readValue(jsonStr, Map.class);
    }
    
    /**
     * json string convert to map with javaBean
     */
    public static <T> Map<String,T> json2map(String jsonStr,Class<T> clazz)throws Exception{
        Map<String,Map<String,Object>> map =  objectMapper.readValue(jsonStr, new TypeReference<Map<String,T>>() {
        });
        Map<String,T> result = new HashMap<String, T>();
        for (Entry<String, Map<String,Object>> entry : map.entrySet()) {
            result.put(entry.getKey(), map2pojo(entry.getValue(), clazz));
        }
        return result;
    }
    
    /**
     * json array string convert to list with javaBean
     */
    public static <T> List<T> json2list(String jsonArrayStr,Class<T> clazz)throws Exception{
        List<Map<String,Object>> list = objectMapper.readValue(jsonArrayStr, new TypeReference<List<T>>() {
        });
        List<T> result = new ArrayList<>();
        for (Map<String, Object> map : list) {
            result.add(map2pojo(map, clazz));
        }
        return result;
    }
    
    /**
     * map convert to javaBean
     */
    public static <T> T map2pojo(Map map,Class<T> clazz){
        return objectMapper.convertValue(map, clazz);
    }
    
    /**
     * json string convert to xml string
     */
    public static String json2xml(String jsonStr)throws Exception{
        JsonNode root = objectMapper.readTree(jsonStr);
        String xml = xmlMapper.writeValueAsString(root);
        return xml;
    }
    
    /**
     * xml string convert to json string
     */
    public static String xml2json(String xml)throws Exception{
        StringWriter w = new StringWriter();
        JsonParser jp = xmlMapper.getFactory().createParser(xml);
        JsonGenerator jg = objectMapper.getFactory().createGenerator(w);
        while (jp.nextToken() != null) {
            jg.copyCurrentEvent(jp);
        }
        jp.close();
        jg.close();
        return w.toString();
    }
    
}

只用了其中的一部分功能，有關annotation部分由於從沒用到因此沒寫，你們能夠自行研究下，我這裏就不提了。jackson的測試代碼以下：

package cn.yangyong.fodder.util;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.junit.Assert;
import org.junit.Test;
import cn.yangyong.fodder.util.JacksonUtils;

public class JacksonUtilsTest {

    @Test
    public void test_pojo2json() throws Exception{
        String json = JacksonUtils.obj2json(new User(1, "張三"));
        Assert.assertEquals("{\"id\":1,\"name\":\"張三\"}", json);
        List<User> list = new ArrayList<>();
        list.add(new User(1, "張三"));
        list.add(new User(2, "李四"));
        String json2 = JacksonUtils.obj2json(list);
        Assert.assertEquals("[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]", json2);
        Map<String,User> map = new HashMap<>();
        map.put("user1", new User(1, "張三"));
        map.put("user2", new User(2, "李四"));
        String json3 = JacksonUtils.obj2json(map);
        Assert.assertEquals("{\"user2\":{\"id\":2,\"name\":\"李四\"},\"user1\":{\"id\":1,\"name\":\"張三\"}}", json3);
    }
    
    @Test
    public void test_json2pojo() throws Exception{
        String json = "{\"id\":1,\"name\":\"張三\"}";
        User user = JacksonUtils.json2pojo(json, User.class);
        Assert.assertTrue(user.getId()==1&&user.getName().equals("張三"));
    }
    
    @Test
    public void test_json2map() throws Exception{
        String json = "{\"id\":1,\"name\":\"張三\"}";
        Map<String,Object> map = JacksonUtils.json2map(json);
        Assert.assertEquals("{id=1, name=張三}", map.toString());
        String json2 = "{\"user2\":{\"id\":2,\"name\":\"李四\"},\"user1\":{\"id\":1,\"name\":\"張三\"}}";
        Map<String,User> map2 = JacksonUtils.json2map(json2, User.class);
        User user1 = map2.get("user1");
        User user2 = map2.get("user2");
        Assert.assertTrue(user1.getId()==1&&user1.getName().equals("張三"));
        Assert.assertTrue(user2.getId()==2&&user2.getName().equals("李四"));
    }
    
    @Test
    public void test_json2list() throws Exception{
        String json = "[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]";
        List<User> list = JacksonUtils.json2list(json,User.class);
        User user1 = list.get(0);
        User user2 = list.get(1);
        Assert.assertTrue(user1.getId()==1&&user1.getName().equals("張三"));
        Assert.assertTrue(user2.getId()==2&&user2.getName().equals("李四"));
    }
    
    @Test
    public void test_map2pojo(){
        Map<String,Object> map = new HashMap<String, Object>();
        map.put("id", 1);
        map.put("name", "張三");
        User user = JacksonUtils.map2pojo(map, User.class);
        Assert.assertTrue(user.getId()==1&&user.getName().equals("張三"));
        System.out.println(user);
    }
    
    @Test
    public void test_json2xml() throws Exception{
        String json = "{\"id\":1,\"name\":\"張三\"}";
        String xml = JacksonUtils.json2xml(json);
        Assert.assertEquals("<ObjectNode xmlns=\"\"><id>1</id><name>張三</name></ObjectNode>", xml);
        String json2 = "{\"Items\":{\"RequestInterfaceSku\":[{\"Sku_ProductNo\":\"sku_0004\"},{\"Sku_ProductNo\":\"sku_0005\"}]}}";
        String xml2 = JacksonUtils.json2xml(json2);
        Assert.assertEquals("<ObjectNode xmlns=\"\"><Items><RequestInterfaceSku><Sku_ProductNo>sku_0004</Sku_ProductNo></RequestInterfaceSku><RequestInterfaceSku><Sku_ProductNo>sku_0005</Sku_ProductNo></RequestInterfaceSku></Items></ObjectNode>", xml2);
    }
    
    @Test
    public void test_xml2json() throws Exception{
        String xml = "<ObjectNode xmlns=\"\"><id>1</id><name>張三</name></ObjectNode>";
        String json = JacksonUtils.xml2json(xml);
        Assert.assertEquals("{\"id\":1,\"name\":\"張三\"}", json);
        String xml2 = "<ObjectNode xmlns=\"\"><Items><RequestInterfaceSku><Sku_ProductNo>sku_0004</Sku_ProductNo></RequestInterfaceSku><RequestInterfaceSku><Sku_ProductNo>sku_0005</Sku_ProductNo></RequestInterfaceSku></Items></ObjectNode>";
        String json2 = JacksonUtils.xml2json(xml2);
        //expected2是咱們想要的格式，但實際結果確實expected1，因此用jackson實現xml直接轉換爲json在遇到數組時是不可行的
        String expected1 = "{\"Items\":{\"RequestInterfaceSku\":{\"Sku_ProductNo\":\"sku_0004\"},\"RequestInterfaceSku\":{\"Sku_ProductNo\":\"sku_0005\"}}}";
        String expected2 = "{\"Items\":{\"RequestInterfaceSku\":[{\"Sku_ProductNo\":\"sku_0004\"},{\"Sku_ProductNo\":\"sku_0005\"}]}}";
        Assert.assertEquals(expected1, json2);
        Assert.assertEquals(expected2, json2);
    }
    
    private static class User{
        private int id;
        private String name; 
        
        public User() {
        }
        public User(int id, String name) {
            this.id = id;
            this.name = name;
        }
        @Override
        public String toString() {
            return "{\"id\":"+id+",\"name\":\""+name+"\"}";
        }
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
    }
}

測試後發現xml轉換爲json時也有問題，竟然不認識數組，真是悲劇。好吧就由它吧，也多是個人方法不正確。

jackson一直很主流，社區和文檔支持也很充足，但有人仍是嫌它不夠快，不夠簡潔，因而便有了fastjson，看名字就知道它的主要特色就是快，可能在功能和其餘支持方面不能和jackson媲美，但天下武功，惟快不破，這就決定了fastjson有了必定的市場。不解釋，直接上代碼。

    <!-- for fastjson -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>1.1.33</version>
    </dependency>

沃，除了自身零依賴，再看它的API使用。
使用fastjson實現多種轉換：

package cn.yangyong.fodder.util;

import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;
import com.alibaba.fastjson.serializer.SerializeConfig;
import com.alibaba.fastjson.serializer.SimpleDateFormatSerializer;

/**
 * fastjson utils
 * 
 * @author magic_yy
 * @see https://github.com/alibaba/fastjson
 * @see http://code.alibabatech.com/wiki/display/FastJSON
 */
public class FastJsonUtils {
    
    private static SerializeConfig mapping = new SerializeConfig();
    
    static{
        mapping.put(Date.class, new SimpleDateFormatSerializer("yyyy-MM-dd HH:mm:ss"));
    }
    
    /**
     * javaBean、list、map convert to json string
     */
    public static String obj2json(Object obj){
//        return JSON.toJSONString(obj,SerializerFeature.UseSingleQuotes);//使用單引號
//        return JSON.toJSONString(obj,true);//格式化數據，方便閱讀
        return JSON.toJSONString(obj,mapping);
    }
    
    /**
     * json string convert to javaBean、map
     */
    public static <T> T json2obj(String jsonStr,Class<T> clazz){
        return JSON.parseObject(jsonStr,clazz);
    }
    
    /**
     * json array string convert to list with javaBean
     */
    public static <T> List<T> json2list(String jsonArrayStr,Class<T> clazz){
        return JSON.parseArray(jsonArrayStr, clazz);
    }
    
    /**
     * json string convert to map
     */
    public static <T> Map<String,Object> json2map(String jsonStr){
        return json2obj(jsonStr, Map.class);
    }
    
    /**
     * json string convert to map with javaBean
     */
    public static <T> Map<String,T> json2map(String jsonStr,Class<T> clazz){
        Map<String,T> map = JSON.parseObject(jsonStr, new TypeReference<Map<String, T>>() {});
        for (Entry<String, T> entry : map.entrySet()) {
            JSONObject obj = (JSONObject) entry.getValue();
            map.put(entry.getKey(), JSONObject.toJavaObject(obj, clazz));
        }
        return map;
    }
}

API真的很簡潔，很方便，這裏依舊只用了部分功能，關於註解部分請你們自行研究。測試代碼以下：

package cn.yangyong.fodder.util;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.junit.Assert;
import org.junit.Test;

public class FastJsonTest {
    
    @Test
    public void test_dateFormat(){
        Date date = new Date();
        String json = FastJsonUtils.obj2json(date);
        String expected = "\""+new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(date)+"\"";
        Assert.assertEquals(expected, json);
    }
    
    @Test
    public void test_obj2json(){
        User user = new User(1, "張三");
        String json = FastJsonUtils.obj2json(user);
        Assert.assertEquals("{\"id\":1,\"name\":\"張三\"}", json);
        List<User> list = new ArrayList<>();
        list.add(new User(1, "張三"));
        list.add(new User(2, "李四"));
        String json2 = FastJsonUtils.obj2json(list);
        Assert.assertEquals("[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]", json2);
        Map<String,User> map = new HashMap<>();
        map.put("user1", new User(1, "張三"));
        map.put("user2", new User(2, "李四"));
        String json3 = FastJsonUtils.obj2json(map);
        Assert.assertEquals("{\"user1\":{\"id\":1,\"name\":\"張三\"},\"user2\":{\"id\":2,\"name\":\"李四\"}}", json3);
    }
    
    @Test
    public void test_json2obj(){
        String json = "{\"id\":1,\"name\":\"張三\"}";
        User user = FastJsonUtils.json2obj(json, User.class);
        Assert.assertTrue(user.getId()==1&&user.getName().equals("張三"));
    }
    
    @Test
    public void test_json2list(){
        String json = "[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]";
        List<User> list = FastJsonUtils.json2list(json, User.class);
        User user1 = list.get(0);
        User user2 = list.get(1);
        Assert.assertTrue(user1.getId()==1&&user1.getName().equals("張三"));
        Assert.assertTrue(user2.getId()==2&&user2.getName().equals("李四"));
    }
    
    @Test
    public void test_json2map() throws Exception{
        String json = "{\"id\":1,\"name\":\"張三\"}";
        Map<String,Object> map = FastJsonUtils.json2map(json);
        Assert.assertEquals("{id=1, name=張三}", map.toString());
        String json2 = "{\"user2\":{\"id\":2,\"name\":\"李四\"},\"user1\":{\"id\":1,\"name\":\"張三\"}}";
        Map<String,User> map2 = FastJsonUtils.json2map(json2, User.class);
        User user1 = map2.get("user1");
        User user2 = map2.get("user2");
        Assert.assertTrue(user1.getId()==1&&user1.getName().equals("張三"));
        Assert.assertTrue(user2.getId()==2&&user2.getName().equals("李四"));
    }
    
    private static class User{
        private int id;
        private String name; 
        
        public User() {
        }
        public User(int id, String name) {
            this.id = id;
            this.name = name;
        }
        @Override
        public String toString() {
            return "{\"id\":"+id+",\"name\":\""+name+"\"}";
        }
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
    }
    
}

只有json和javaBean直接的相互轉換，沒有xml的轉換，真惋惜。好吧，誰叫人家定位不同呢，要想功能全仍是用jackson吧。

最後給你們介紹下json和xml之間不依賴javaBean直接相互轉換的工具staxon，相比不少時候你們都想動態的將json和xml相互轉換卻不依賴其餘javaBean，本身寫真的是很麻煩，要人命，用jackson等其餘轉換工具時結果都不是我想要的

好比有下面xml和json，他們是等價的：

<Response>
    <CustID>1300000428</CustID>
    <CompID>1100000324</CompID>
    <Items>
        <Item>
            <Sku_ProductNo>sku_0004</Sku_ProductNo>
            <Wms_Code>1700386977</Wms_Code>
            <Sku_Response>T</Sku_Response>
            <Sku_Reason></Sku_Reason>
        </Item>
        <Item>
            <Sku_ProductNo>0005</Sku_ProductNo>
            <Wms_Code>1700386978</Wms_Code>
            <Sku_Response>T</Sku_Response>
            <Sku_Reason></Sku_Reason>
        </Item>
    </Items>
</Response>

{
    "Response" : {
        "CustID" : 1300000428,
        "CompID" : 1100000324,
        "Items" : {
            "Item" : [ {
                "Sku_ProductNo" : "sku_0004",
                "Wms_Code" : 1700386977,
                "Sku_Response" : "T",
                "Sku_Reason" : null
            }, {
                "Sku_ProductNo" : "0005",
                "Wms_Code" : 1700386978,
                "Sku_Response" : "T",
                "Sku_Reason" : null
            } ]
        }
    }
}

下面咱們使用staxon來實現上面2種互轉

        <!-- for staxon -->
    <dependency>
        <groupId>de.odysseus.staxon</groupId>
        <artifactId>staxon</artifactId>
        <version>1.2</version>
    </dependency>

嗯，沒有第三方依賴，上轉換代碼：

package cn.yangyong.fodder.util;

import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;

import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLEventWriter;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLOutputFactory;

import de.odysseus.staxon.json.JsonXMLConfig;
import de.odysseus.staxon.json.JsonXMLConfigBuilder;
import de.odysseus.staxon.json.JsonXMLInputFactory;
import de.odysseus.staxon.json.JsonXMLOutputFactory;
import de.odysseus.staxon.xml.util.PrettyXMLEventWriter;

/**
 * json and xml converter
 * @author magic_yy
 * @see https://github.com/beckchr/staxon
 * @see https://github.com/beckchr/staxon/wiki
 *
 */
public class StaxonUtils {
    
    /**
     * json string convert to xml string
     */
    public static String json2xml(String json){
        StringReader input = new StringReader(json);
        StringWriter output = new StringWriter();
        JsonXMLConfig config = new JsonXMLConfigBuilder().multiplePI(false).repairingNamespaces(false).build();
        try {
            XMLEventReader reader = new JsonXMLInputFactory(config).createXMLEventReader(input);
            XMLEventWriter writer = XMLOutputFactory.newInstance().createXMLEventWriter(output);
            writer = new PrettyXMLEventWriter(writer);
            writer.add(reader);
            reader.close();
            writer.close();
        } catch( Exception e){
            e.printStackTrace();
        } finally {
            try {
                output.close();
                input.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if(output.toString().length()>=38){//remove <?xml version="1.0" encoding="UTF-8"?>
            return output.toString().substring(39);
        }
        return output.toString();
    }
    
    /**
     * xml string convert to json string
     */
    public static String xml2json(String xml){
        StringReader input = new StringReader(xml);
        StringWriter output = new StringWriter();
        JsonXMLConfig config = new JsonXMLConfigBuilder().autoArray(true).autoPrimitive(true).prettyPrint(true).build();
        try {
            XMLEventReader reader = XMLInputFactory.newInstance().createXMLEventReader(input);
            XMLEventWriter writer = new JsonXMLOutputFactory(config).createXMLEventWriter(output);
            writer.add(reader);
            reader.close();
            writer.close();
        } catch( Exception e){
            e.printStackTrace();
        } finally {
            try {
                output.close();
                input.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return output.toString();
    }
}

固然，這裏我也就只用到了它的部分功能，最主要的仍是json和xml直接的轉換了撒。其餘功能本身看咯，很少作介紹了。測試代碼以下：

package cn.yangyong.fodder.util;

import org.junit.Test;

public class StaxonUtilsTest {
    
    @Test
    public void test_json2xml(){
        String json = "{\"Response\" : {\"CustID\" : 1300000428,\"CompID\" : 1100000324,\"Items\" : {\"Item\" : [ {\"Sku_ProductNo\" : \"sku_0004\",\"Wms_Code\" : 1700386977,\"Sku_Response\" : \"T\",\"Sku_Reason\" : null}, {\"Sku_ProductNo\" : \"0005\",\"Wms_Code\" : 1700386978,\"Sku_Response\" : \"T\",\"Sku_Reason\" : null}]}}}";
        String xml = StaxonUtils.json2xml(json);
        System.out.println(xml);
    }
    
    @Test
    public void test_xml2json(){
        String xml = "<Response><CustID>1300000428</CustID><CompID>1100000324</CompID><Items><Item><Sku_ProductNo>sku_0004</Sku_ProductNo><Wms_Code>1700386977</Wms_Code><Sku_Response>T</Sku_Response><Sku_Reason></Sku_Reason></Item><Item><Sku_ProductNo>0005</Sku_ProductNo><Wms_Code>1700386978</Wms_Code><Sku_Response>T</Sku_Response><Sku_Reason></Sku_Reason></Item></Items></Response>";
        String json = StaxonUtils.xml2json(xml);
        System.out.println(json);
    }
}