使用Gson解析常见json字符串

日常开发中常遇到的json字符串主要有三种：

1）简单的json object  字符串

      String jsonObjectStr = "{\"name\":\"zhangsan\",\"age\":\"18\"}";

2）json array 字符串

      String jsonArrayStr = "[{\"name\":\"zhangsan\",\"age\":\"18\"},{\"name\":\"lisi\",\"age\":\"28\"}]";

3）稍微复杂点的json object 字符串

      String jsonSpecialStr = "{\"school\":\"NanJingDaXue\",\"city\":\"najing\",\"peoples\":[{\"name\":\"zhangsan\",\"age\":\"18\"},{\"name\":\"zhangsan\",\"age\":\"18\"}]}";

解析json的方法很多，这里总结下使用Gson解析以上三种json字符串的方法：

1、首先新建一个maven工程，pom文件中引入gson的依赖项：

<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.2.2</version>
</dependency>

2、根据前面提到的json字符串结构，可定义反序列化对象People类、Students：

package com.zgy.json.info;

public class People
{
//name
private String name;

//age
private String age;

/**
* @return the name
*/
public String getName()
{
return name;
}

/**
* @param name the name to set
*/
public void setName(String name)
{
this.name = name;
}

/* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString()
{
StringBuilder builder = new StringBuilder();
builder.append("People [name=");
builder.append(name);
builder.append(", age=");
builder.append(age);
builder.append("]");
return builder.toString();
}
}

package com.zgy.json.info;

import java.util.Arrays;
import com.google.gson.annotations.SerializedName;

public class Students
{
private String school;

@SerializedName("city")  //注解，当json字符串中的字段定义和所需的不同时，可用注解标注
private String city;

private People [] peoples;

/**
* @return the school
*/
public String getSchool()
{
return school;
}

/**
* @param school the school to set
*/
public void setSchool(String school)
{
this.school = school;
}

/* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString()
{
StringBuilder builder = new StringBuilder();
builder.append("Students [school=");
builder.append(school);
builder.append(", city=");
builder.append(city);
builder.append(", peoples=");
builder.append(Arrays.toString(peoples));
builder.append("]");
return builder.toString();
}
}

3、简单的json object  字符串的解析

Code: 

String jsonObjectStr = "{\"name\":\"zhangsan\",\"age\":\"18\"}";
Gson gson = new Gson();
People people = gson.fromJson(jsonObjectStr, People.class);
System.out.println(people.toString());

解析结果：

People [name=zhangsan, age=18]

4、json array 字符串的解析

Code:    

String jsonArrayStr = "[{\"name\":\"zhangsan\",\"age\":\"18\"},{\"name\":\"lisi\",\"age\":\"28\"}]";
Gson gson = new Gson();

People[] peoples = gson.fromJson(jsonArrayStr, People[].class);

for (People x : peoples)
{
System.out.println(x.toString());
}

解析结果：

People [name=zhangsan, age=18]

People [name=lisi, age=28]

5、第三种复杂json

 

Code:    

String jsonSpecialStr = "{\"school\":\"NanJingDaXue\",\"city\":\"nanjing\",\"peoples\":[{\"name\":\"zhangsan\",\"age\":\"18\"},

{\"name\":\"lisi\",\"age\":\"28\"}]}";
Gson gson = new Gson();

Students students = gson.fromJson(jsonSpecialStr, Students.class);
System.out.println(students.toString());

解析结果：

Students [school=NanJingDaXue, city=nanjing, peoples=[People [name=zhangsan, age=18], People [name=lisi, age=28]]]