Android：修改鏈接到AP端顯示的設備名

1、Android系統代碼中實現設備名分配

　　1. \frameworks\base\services\core\java\com\android\server\ConnectivityService.java

　　　 創建鏈接時讀取 "net.hostname" 屬性值是否爲空，若是爲空則獲取設備id，加上"android-"前綴並設置到屬性：

protected ConnectivityService(Context context, INetworkManagementService netManager,
            INetworkStatsService statsService, INetworkPolicyManager policyManager,
            IpConnectivityLog logger) {
            mHandlerThread = new HandlerThread("ConnectivityServiceThread");
        mHandlerThread.start();
        mHandler = new InternalHandler(mHandlerThread.getLooper());
        mTrackerHandler = new NetworkStateTrackerHandler(mHandlerThread.getLooper());

        // setup our unique device name
        if (TextUtils.isEmpty(SystemProperties.get("net.hostname"))) { String id = Settings.Secure.getString(context.getContentResolver(), Settings.Secure.ANDROID_ID); if (id != null && id.length() > 0) { String name = new String("android-").concat(id); SystemProperties.set("net.hostname", name); } }
　　　　　......
}

　　2. \frameworks\base\services\net\java\android\net\dhcp\DhcpInformPacket.java

　　　經過 addCommonClientTlvs() 接口獲取設備ID並填入buffer:

    /**
     * Adds additional parameters to the INFORM packet.
     */
    void finishPacket(ByteBuffer buffer) {
        addTlv(buffer, DHCP_MESSAGE_TYPE, DHCP_MESSAGE_TYPE_INFORM);
        addTlv(buffer, DHCP_CLIENT_IDENTIFIER, getClientId());
        addCommonClientTlvs(buffer);
        addTlv(buffer, DHCP_PARAMETER_LIST, mRequestedParams);
        addTlvEnd(buffer);
    }

　　調用到 \frameworks\base\services\net\java\android\net\dhcp\DhcpPacket.java 中獲取 "net.hostname" 屬性值，

　　添加到Tlv信息中（TLV是一種編碼方式，由數據的類型Tag，數據的長度Length，數據的內容Value構成的一組數據報文）   

    protected void addCommonClientTlvs(ByteBuffer buf) {
        addTlv(buf, DHCP_MAX_MESSAGE_SIZE, (short) MAX_LENGTH);
        Option60 option60 = null;

        if (mIface != null) {
            option60 = OptionManager.getInstance().getOption60(mIface);
        }

        if (option60 != null && option60.getOptionSwitch() != 0
            && option60.getLogin() != null && option60.getPassword() != null){
            byte[] dhcpPlusBuf = buildDhcpPlusMsg(option60.getLogin(),option60.getPassword());
            addTlv(buf,DHCP_VENDOR_CLASS_ID,dhcpPlusBuf);
        } else {
            addTlv(buf, DHCP_VENDOR_CLASS_ID, getVendorId());
        }
        final String hn = getHostname(); if (!TextUtils.isEmpty(hn)) addTlv(buf, DHCP_HOST_NAME, hn);
    }

　　getHostname() 實現：

    private String getHostname() {
        if (testOverrideHostname != null) return testOverrideHostname;
        return SystemProperties.get("net.hostname");
    }

　　 addTlv() 實現：

    /**
     * Adds an optional parameter containing an array of bytes.
     */
    protected static void addTlv(ByteBuffer buf, byte type, byte[] payload) {
        if (payload != null) {
            if (payload.length > MAX_OPTION_LEN) {
                throw new IllegalArgumentException("DHCP option too long: "
                        + payload.length + " vs. " + MAX_OPTION_LEN);
            }
            buf.put(type);
            buf.put((byte) payload.length);
            buf.put(payload);
        }
    }

　　編譯及更新：

mmm frameworks/base/services/
adb push out/target/product/almond/system/framework/services.jar /system/framework/
adb push out/target/product/almond/system/framework/oat/arm64/services.odex /system/framework/oat/arm64/   （優化編譯纔有此目錄）

　　

2、經過build.prop文件配置設備名

　　1. 修改 /system/build.prop 最後添加，### 爲本身設置的設備名：

net.hostname=###

　　2. 重啓、重連wifi，從熱點或路由器後臺查看設備名即爲修改後的名稱。