使用FastJson处理JSON数据

一、简介

FastJson对于json格式字符串的解析主要用到了下面三个类： 
1.JSON：fastJson的解析器，用于JSON格式字符串与JSON对象及javaBean之间的转换 
2.JSONObject：fastJson提供的json对象 
3.JSONArray：fastJson提供json数组对象

<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>fastjson</artifactId>
  <version>1.2.47</version>
</dependency>

二、使用

定义三个json字符串

//json字符串-简单对象型
private static final String  JSON_OBJ_STR = "{"studentName":"lily","studentAge":12}";

//json字符串-数组类型
private static final String  JSON_ARRAY_STR = "[{"studentName":"lily","studentAge":12},{"studentName":"lucy","studentAge":15}]";

//复杂格式json字符串
private static final String  COMPLEX_JSON_STR = "{"teacherName":"crystall","teacherAge":27,"course":{"courseName":"english","code":1270},"students":[{"studentName":"lily","studentAge":12},{"studentName":"lucy","studentAge":15}]}";

2.1.JSON格式字符串与JSON对象之间的转换

2.1.1.json字符串-简单对象型与JSONObject之间的转换

/**
 * json字符串-简单对象型到JSONObject的转换
 */
@Test
public void testJSONStrToJSONObject() {

    JSONObject jsonObject = JSONObject.parseObject(JSON_OBJ_STR);

    System.out.println("studentName:  " + jsonObject.getString("studentName") + ":" + "  studentAge:  "
            + jsonObject.getInteger("studentAge"));

}

/**
 * JSONObject到json字符串-简单对象型的转换
 */
@Test
public void testJSONObjectToJSONStr() {

    //已知JSONObject,目标要转换为json字符串
    JSONObject jsonObject = JSONObject.parseObject(JSON_OBJ_STR);
    // 第一种方式
    String jsonString = JSONObject.toJSONString(jsonObject);

    // 第二种方式
    //String jsonString = jsonObject.toJSONString();
    System.out.println(jsonString);
}

2.1.2.json字符串(数组类型)与JSONArray之间的转换

/**
 * json字符串-数组类型到JSONArray的转换
 */
@Test
public void testJSONStrToJSONArray() {

    JSONArray jsonArray = JSONArray.parseArray(JSON_ARRAY_STR);

    //遍历方式1
    int size = jsonArray.size();
    for (int i = 0; i < size; i++) {

        JSONObject jsonObject = jsonArray.getJSONObject(i);
        System.out.println("studentName:  " + jsonObject.getString("studentName") + ":" + "  studentAge:  "
                + jsonObject.getInteger("studentAge"));
    }

    //遍历方式2
    for (Object obj : jsonArray) {

        JSONObject jsonObject = (JSONObject) obj;
        System.out.println("studentName:  " + jsonObject.getString("studentName") + ":" + "  studentAge:  "
                + jsonObject.getInteger("studentAge"));
    }
}

/**
 * JSONArray到json字符串-数组类型的转换
 */
@Test
public void testJSONArrayToJSONStr() {

    //已知JSONArray,目标要转换为json字符串
    JSONArray jsonArray = JSONArray.parseArray(JSON_ARRAY_STR);
    //第一种方式
    String jsonString = JSONArray.toJSONString(jsonArray);

    // 第二种方式
    //String jsonString = jsonArray.toJSONString(jsonArray);
    System.out.println(jsonString);
}

2.1.3.复杂json格式字符串与JSONObject之间的转换

/**
 * 复杂json格式字符串到JSONObject的转换
 */
@Test
public void testComplexJSONStrToJSONObject() {

    JSONObject jsonObject = JSONObject.parseObject(COMPLEX_JSON_STR);

    String teacherName = jsonObject.getString("teacherName");
    Integer teacherAge = jsonObject.getInteger("teacherAge");

    System.out.println("teacherName:  " + teacherName + "   teacherAge:  " + teacherAge);

    JSONObject jsonObjectcourse = jsonObject.getJSONObject("course");
     //获取JSONObject中的数据
    String courseName = jsonObjectcourse.getString("courseName");
    Integer code = jsonObjectcourse.getInteger("code");

    System.out.println("courseName:  " + courseName + "   code:  " + code);

    JSONArray jsonArraystudents = jsonObject.getJSONArray("students");

    //遍历JSONArray
    for (Object object : jsonArraystudents) {

        JSONObject jsonObjectone = (JSONObject) object;
        String studentName = jsonObjectone.getString("studentName");
        Integer studentAge = jsonObjectone.getInteger("studentAge");

        System.out.println("studentName:  " + studentName + "   studentAge:  " + studentAge);
    }
}

/**
 * 复杂JSONObject到json格式字符串的转换
 */
@Test
public void testJSONObjectToComplexJSONStr() {

   //复杂JSONObject,目标要转换为json字符串
    JSONObject jsonObject = JSONObject.parseObject(COMPLEX_JSON_STR);

    //第一种方式
    //String jsonString = JSONObject.toJSONString(jsonObject);

    //第二种方式
    String jsonString = jsonObject.toJSONString();
    System.out.println(jsonString);

}

2.2.JSON格式字符串与javaBean之间的转换

2.2.1.json字符串-简单对象型与javaBean之间的转换

/**
 * json字符串-简单对象到JavaBean之间的转换
 */
@Test
public void testJSONStrToJavaBeanObj() {

    //第一种方式
    JSONObject jsonObject = JSONObject.parseObject(JSON_OBJ_STR);

    String studentName = jsonObject.getString("studentName");
    Integer studentAge = jsonObject.getInteger("studentAge");

    //Student student = new Student(studentName, studentAge);

    //第二种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    //Student student = JSONObject.parseObject(JSON_OBJ_STR, new TypeReference<Student>() {});

    //第三种方式,使用Gson的思想
    Student student = JSONObject.parseObject(JSON_OBJ_STR, Student.class);

    System.out.println(student);
}

/**
 * JavaBean到json字符串-简单对象的转换
 */
@Test
public void testJavaBeanObjToJSONStr() {

    Student student = new Student("lily", 12);
    String jsonString = JSONObject.toJSONString(student);
    System.out.println(jsonString);
}

2.2.2.json字符串-数组类型与javaBean之间的转换

/**
 * json字符串-数组类型到JavaBean_List的转换
 */
@Test
public void testJSONStrToJavaBeanList() {

    //第一种方式
    JSONArray jsonArray = JSONArray.parseArray(JSON_ARRAY_STR);

    //遍历JSONArray
    List<Student> students = new ArrayList<Student>();
    Student student = null;
    for (Object object : jsonArray) {

        JSONObject jsonObjectone = (JSONObject) object;
        String studentName = jsonObjectone.getString("studentName");
        Integer studentAge = jsonObjectone.getInteger("studentAge");

        student = new Student(studentName,studentAge);
        students.add(student);
    }

    System.out.println("students:  " + students);


    //第二种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    List<Student> studentList = JSONArray.parseObject(JSON_ARRAY_STR, new TypeReference<ArrayList<Student>>() {});
    System.out.println("studentList:  " + studentList);

    //第三种方式,使用Gson的思想
    List<Student> studentList1 = JSONArray.parseArray(JSON_ARRAY_STR, Student.class);
    System.out.println("studentList1:  " + studentList1);

}

/**
 * JavaBean_List到json字符串-数组类型的转换
 */
@Test
public void testJavaBeanListToJSONStr() {

    Student student = new Student("lily", 12);
    Student studenttwo = new Student("lucy", 15);

    List<Student> students = new ArrayList<Student>();
    students.add(student);
    students.add(studenttwo);

    String jsonString = JSONArray.toJSONString(students);
    System.out.println(jsonString);

}

2.2.3.复杂json格式字符串与与javaBean之间的转换

/**
 * 复杂json格式字符串到JavaBean_obj的转换
 */
@Test
public void testComplexJSONStrToJavaBean(){

    //第一种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    Teacher teacher = JSONObject.parseObject(COMPLEX_JSON_STR, new TypeReference<Teacher>() {});
    System.out.println(teacher);

    //第二种方式,使用Gson思想
    Teacher teacher1 = JSONObject.parseObject(COMPLEX_JSON_STR, Teacher.class);
    System.out.println(teacher1);
}

/**
 * 复杂JavaBean_obj到json格式字符串的转换
 */
@Test
public void testJavaBeanToComplexJSONStr(){

    //已知复杂JavaBean_obj
    Teacher teacher = JSONObject.parseObject(COMPLEX_JSON_STR, new TypeReference<Teacher>() {});
    String jsonString = JSONObject.toJSONString(teacher);
    System.out.println(jsonString);
}

2.3.javaBean与json对象间的之间的转换

2.3.1.简单javaBean与json对象之间的转换

/**
 * 简单JavaBean_obj到json对象的转换
 */
@Test
public void testJavaBeanToJSONObject(){

    //已知简单JavaBean_obj
    Student student = new Student("lily", 12);

    //方式一
    String jsonString = JSONObject.toJSONString(student);
    JSONObject jsonObject = JSONObject.parseObject(jsonString);
    System.out.println(jsonObject);

    //方式二
    JSONObject jsonObject1 = (JSONObject) JSONObject.toJSON(student);
    System.out.println(jsonObject1);
}

/**
 * 简单json对象到JavaBean_obj的转换
 */
@Test
public void testJSONObjectToJavaBean(){

    //已知简单json对象
    JSONObject jsonObject = JSONObject.parseObject(JSON_OBJ_STR);

    //第一种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    Student student = JSONObject.parseObject(jsonObject.toJSONString(), new TypeReference<Student>() {});
    System.out.println(student);

    //第二种方式,使用Gson的思想
    Student student1 = JSONObject.parseObject(jsonObject.toJSONString(), Student.class);
    System.out.println(student1);
}

2.3.2.JavaList与JsonArray之间的转换

/**
 * JavaList到JsonArray的转换
 */
@Test
public void testJavaListToJsonArray() {

    //已知JavaList
    Student student = new Student("lily", 12);
    Student studenttwo = new Student("lucy", 15);

    List<Student> students = new ArrayList<Student>();
    students.add(student);
    students.add(studenttwo);

    //方式一
    String jsonString = JSONArray.toJSONString(students);
    JSONArray jsonArray = JSONArray.parseArray(jsonString);
    System.out.println(jsonArray);

    //方式二
    JSONArray jsonArray1 = (JSONArray) JSONArray.toJSON(students);
    System.out.println(jsonArray1);
}

/**
 * JsonArray到JavaList的转换
 */
@Test
public void testJsonArrayToJavaList() {

    //已知JsonArray
    JSONArray jsonArray = JSONArray.parseArray(JSON_ARRAY_STR);

    //第一种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    ArrayList<Student> students = JSONArray.parseObject(jsonArray.toJSONString(),
            new TypeReference<ArrayList<Student>>() {});

    System.out.println(students);

    //第二种方式,使用Gson的思想
    List<Student> students1 = JSONArray.parseArray(jsonArray.toJSONString(), Student.class);
    System.out.println(students1);
}

2.3.3.复杂JavaBean_obj与json对象之间的转换

/**
 * 复杂JavaBean_obj到json对象的转换
 */
@Test
public void testComplexJavaBeanToJSONObject() {

    //已知复杂JavaBean_obj
    Student student = new Student("lily", 12);
    Student studenttwo = new Student("lucy", 15);

    List<Student> students = new ArrayList<Student>();
    students.add(student);
    students.add(studenttwo);
    Course course = new Course("english", 1270);

    Teacher teacher = new Teacher("crystall", 27, course, students);

    //方式一
    String jsonString = JSONObject.toJSONString(teacher);
    JSONObject jsonObject = JSONObject.parseObject(jsonString);
    System.out.println(jsonObject);

    //方式二
    JSONObject jsonObject1 = (JSONObject) JSONObject.toJSON(teacher);
    System.out.println(jsonObject1);

}

/**
 * 复杂json对象到JavaBean_obj的转换
 */
@Test
public void testComplexJSONObjectToJavaBean() {

    //已知复杂json对象
    JSONObject jsonObject = JSONObject.parseObject(COMPLEX_JSON_STR);

    //第一种方式,使用TypeReference<T>类,由于其构造方法使用protected进行修饰,故创建其子类
    Teacher teacher = JSONObject.parseObject(jsonObject.toJSONString(), new TypeReference<Teacher>() {});
    System.out.println(teacher);

    //第二种方式,使用Gson的思想
    Teacher teacher1 = JSONObject.parseObject(jsonObject.toJSONString(), Teacher.class);
    System.out.println(teacher1);
}