Android网络编程之操作JSON对象库-Gson

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之前在Volley框架JsonObjectRequest和JsonArrayRequest的使用中搭配了Gson库，操作JSON数据格式非常方便，所以这里详细阐述下Gson的使用方法。

Gson下载地址:http://code.google.com/p/google-gson/downloads/list

Gson主要提供两种方法：toJson序列化方法以及fromJson反序列化方法。从字面意思可以理解，toJson是将一种数据格式转换为JSON格式，fromJson则是将JSON格式转换为其他数据格式。

1.序列化及反序列化

下面的代码片段列出了封装的集中常见格式的转换

import java.lang.reflect.Type;import java.util.List;import java.util.Map;import com.google.gson.FieldNamingPolicy;import com.google.gson.Gson;import com.google.gson.GsonBuilder;public class GsonUtils {    private GsonUtils gsonUtils;    public GsonUtils() {        // TODO Auto-generated constructor stub    }    public GsonUtils getInstance() {        if (gsonUtils == null) {            gsonUtils = new GsonUtils();        }        return gsonUtils;    }    public static Gson getGsonBuilder() {        Gson gson = new GsonBuilder()// GSONBUILDER实现更高级的一些序列化反序列化操作                // 自定义JSON序列化反序列化类，实现自己的需求                // .registerTypeAdapter(Id.class, new IdTypeAdapter())                .excludeFieldsWithoutExposeAnnotation() // 不导出实体中没有用@Expose注解的属性                .enableComplexMapKeySerialization() // 支持Map的key为复杂对象的形式                .serializeNulls()// 序列化空字段。默认情况下，GSON省略所有序列化过程中的空字段                .setDateFormat("yyyy-MM-dd HH:mm:ss:SSS")// 时间转化为特定格式                .setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE)// 会把字段首字母大写,注:对于实体上使用了@SerializedName注解的不会生效.                .setPrettyPrinting() // 格式化输出，只影响序列化输出JSON.                .disableHtmlEscaping() // 设置显示HTML特殊字符，如&lt; &gt;等等，不设置默认忽略这些字符                .setVersion(1.0) // 高于1.0版本的字段序列化和反序列化的时候忽略                .create();        return gson;    }    public static Gson getGson() {        Gson gson = new Gson();        return gson;    }    // 各种数据格式转换为JSON    public static String toJson(Gson gson, Object object) {        String msg = gson.toJson(object);        return msg;    }    // JSON转换为字符串    public static String jsonToString(Gson gson, String string, Type typeOfT) {        String msg = gson.fromJson(string, typeOfT);        return msg;    }    // JSON转换为Map    public static Map<String, Object> jsonToMap(Gson gson, String string, Type typeOfT) {        Map<String, Object> msg = gson.fromJson(string, typeOfT);        return msg;    }    // JSON转换为普通List    public static List<Map<String, Object>> jsonToList(Gson gson, String string, Type typeOfT) {        List<Map<String, Object>> msg = gson.fromJson(string, typeOfT);        return msg;    }    // JSON转换为List对象    public static List<People> jsonToListB(Gson gson, String string, Type typeOfT) {        List<People> msg = gson.fromJson(string, typeOfT);        return msg;    }}

2.用到的一些数据集合

import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;public class DataUtils {    private static DataUtils dataUtils;    public DataUtils() {        // TODO Auto-generated constructor stub    }    public DataUtils getInstance() {        if (dataUtils == null) {            dataUtils = new DataUtils();        }        return dataUtils;    }    // 获取String数组    public static String[][] getStringArrays() {        return new String[][] { { "gaoruan", "22", "true" }, { "xudong", "22", "false", "true" } };    }    // 获取map    public static Map<String, Object> getMap(String name, int age, int height, boolean isfool) {        Map<String, Object> map = new HashMap<String, Object>();        map.put("name", name);        map.put("age", age);        map.put("height", height);        map.put("isfool", isfool);        People people1 = new People();        people1.setName("xudong");        people1.setAge(22);        people1.setHeight(122);        People people2 = new People();        people2.setName("zhangming");        people2.setAge(22);        people2.setHeight(122);        List<People> list = new ArrayList<People>();        list.add(people1);        list.add(people2);        map.put("peoples", list);        return map;    }    // 获取list    public static List<Map<String, Object>> getList() {        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();        list.add(getMap("gaoruan", 22, 122, true));        Map<String, Object> map = getMap("xudong", 22, 122, true);        map.put("weight", 222);        map.put("ismarried", false);        list.add(map);        return list;    }    // 获取list<people>    public static List<People> getPeopleList() {        List<People> list = new ArrayList<People>();        list.add(new People("xudong", 22, 122, 222, false, true));        People people = new People();        people.setName("gaoruan");        people.setAge(22);        people.setHeight(122);        list.add(people);        return list;    }}

3.用到的JavaBean

import com.google.gson.annotations.Expose;import com.google.gson.annotations.SerializedName;import com.google.gson.annotations.Since;import com.google.gson.annotations.Until;public class People {    @Expose    String name;    @Expose(deserialize = false) // 反序列化时删除此字段 default true    int age;    @Expose(serialize = false) // 序列化时删除此字段 default true    int height;    @Expose    @Since(1.1) // 1.0版本增加此字段    @Until(3.0) // 3.0版本删除此字段    int weight;    @Expose    @Since(1.1)    boolean ismarried;    @Expose    @SerializedName(value = "fool") // 设置序列化和反序列化时的替代字段名称    boolean isfool;    public People() {        // TODO Auto-generated constructor stub    }    public People(String name, int age, int height, int weight, boolean ismarried, boolean isfool) {        // TODO Auto-generated constructor stub        this.name = name;        this.age = age;        this.height = height;        this.weight = weight;        this.ismarried = ismarried;        this.isfool = isfool;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    public int getHeight() {        return height;    }    public void setHeight(int height) {        this.height = height;    }    public int getWeight() {        return weight;    }    public void setWeight(int weight) {        this.weight = weight;    }    public boolean isIsmarried() {        return ismarried;    }    public void setIsmarried(boolean ismarried) {        this.ismarried = ismarried;    }    public boolean isIsfool() {        return isfool;    }    public void setIsfool(boolean isfool) {        this.isfool = isfool;    }    @Override    public String toString() {        return "People [name=" + name + ", age=" + age + ", height=" + height + ", weight=" + weight + ", ismarried="                + ismarried + ", isfool=" + isfool + "]";    }}

4.方法调用Activity

import java.util.List;import java.util.Map;import com.google.gson.Gson;import com.google.gson.reflect.TypeToken;import com.ruan.test.LogUtils;import android.app.Activity;import android.os.Bundle;public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        new GsonUtils().getInstance();        new DataUtils();        // Gson gson = GsonUtils.getGson();        Gson gson = GsonUtils.getGsonBuilder();        // String msg = GsonUtils.toJson(gson, DataUtils.getStringArrays());        // String msg = GsonUtils.toJson(gson, DataUtils.getList());        // String msg = GsonUtils.toJson(gson, DataUtils.getPeopleList());        /**         * Map List<Bean> List<Map>与JSON相互转换         */        String msg = GsonUtils.toJson(gson, DataUtils.getMap("gaoruan", 22, 122, true));        Map<String, Object> msg2 = GsonUtils.jsonToMap(gson, msg, new TypeToken<Map<String, Object>>() {        }.getType());        LogUtils.e(msg);        for (String key : msg2.keySet()) {            if (key.equals("peoples")) {                // String msg3 = GsonUtils.jsonToString(gson,string, typeOfT)                List<People> msg3 = GsonUtils.jsonToListB(gson, msg2.get(key).toString(),                        new TypeToken<List<People>>() {                        }.getType());                for (People people : msg3) {                    LogUtils.e(("name:" + people.getName() + " age:" + people.getAge()));                }            } else                LogUtils.e(("key:" + key + " values:" + msg2.get(key)));        }        // String msg = GsonUtils.toJson(gson,DataUtils.getList());        // LogUtils.e(msg);        // List<Map<String, Object>> msg2 = GsonUtils.jsonToList(gson,msg, new        // TypeToken<List<Map<String, Object>>>() {        // }.getType());        // for (Map<String, Object> map : msg2) {        // for (String key : map.keySet()) {        // LogUtils.e(("keys:" + key + " values:" + map.get(key)));        // }        //        // }    }}

5.总结

1.Gson主要用作JSON格式数据的序列化反序列化，一些简单的操作例如JSONObject和JSONArray可以完成的没必要套用Gson来操作。
2.敬请期待。

6.源码地址

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