Json转换利器Gson之实例五-实际开发中的特殊需求处理

最新推荐文章于 2021-02-15 22:04:17 发布

转载最新推荐文章于 2021-02-15 22:04:17 发布 · 432 阅读

Json 专栏收录该内容

6 篇文章

订阅专栏

本文详细介绍了如何处理具有特定结构的JSON串，包括定义实体类、实现对象转JSON及JSON转对象的过程，并提供了实例代码进行演示。

前面四篇博客基本上可以满足我们处理的绝大多数需求,但有时项目中对json有特殊的格式规定.比如下面的json串解析:

[{"tableName":"students","tableData":[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 9:54:49 PM"},{"id":2,"name":"曹贵生","birthDay":"Jun 22, 2012 9:54:49 PM"},{"id":3,"name":"柳波","birthDay":"Jun 22, 2012 9:54:49 PM"}]},{"tableName":"teachers","tableData":[{"id":1,"name":"米老师","title":"教授"},{"id":2,"name":"丁老师","title":"讲师"}]}]

分析之后我们发现使用前面博客中用到的都不好处理上面的json串.请看本文是如何处理的吧:

实体类:

import java.util.Date;

public class Student {
	private int id;
	private String name;
	private Date birthDay;

	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;
	}

	public Date getBirthDay() {
		return birthDay;
	}

	public void setBirthDay(Date birthDay) {
		this.birthDay = birthDay;
	}

	@Override
	public String toString() {
		return "Student [birthDay=" + birthDay + ", id=" + id + ", name="
				+ name + "]";
	}

}

public class Teacher {
	private int id;

	private String name;

	private String title;

	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;
	}

	public String getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}

	@Override
	public String toString() {
		return "Teacher [id=" + id + ", name=" + name + ", title=" + title
				+ "]";
	}

}

注意这里定义了一个TableData实体类:

import java.util.List;

public class TableData {

	private String tableName;

	private List tableData;

	public String getTableName() {
		return tableName;
	}

	public void setTableName(String tableName) {
		this.tableName = tableName;
	}

	public List getTableData() {
		return tableData;
	}

	public void setTableData(List tableData) {
		this.tableData = tableData;
	}
}

测试类:

(仔细看将json转回为对象的实现,这里经过两次转化,第一次转回的结果是map不是我们所期望的对象,对map再次转为json后再转为对象,我引用的是Gson2.1的jar处理正常,好像使用Gson1.6的jar会报错,所以建议用最新版本)

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class GsonTest5 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// 对象转为Json-->start
		Student student1 = new Student();
		student1.setId(1);
		student1.setName("李坤");
		student1.setBirthDay(new Date());

		Student student2 = new Student();
		student2.setId(2);
		student2.setName("曹贵生");
		student2.setBirthDay(new Date());

		Student student3 = new Student();
		student3.setId(3);
		student3.setName("柳波");
		student3.setBirthDay(new Date());

		List<Student> stulist = new ArrayList<Student>();
		stulist.add(student1);
		stulist.add(student2);
		stulist.add(student3);

		Teacher teacher1 = new Teacher();
		teacher1.setId(1);
		teacher1.setName("米老师");
		teacher1.setTitle("教授");

		Teacher teacher2 = new Teacher();
		teacher2.setId(2);
		teacher2.setName("丁老师");
		teacher2.setTitle("讲师");
		List<Teacher> teacherList = new ArrayList<Teacher>();
		teacherList.add(teacher1);
		teacherList.add(teacher2);

		TableData td1 = new TableData();
		td1.setTableName("students");
		td1.setTableData(stulist);

		TableData td2 = new TableData();
		td2.setTableName("teachers");
		td2.setTableData(teacherList);

		List<TableData> tdList = new ArrayList<TableData>();
		tdList.add(td1);
		tdList.add(td2);
		Gson gson = new Gson();
		String s = gson.toJson(tdList);

		System.out.println(s);
		// 结果:[{"tableName":"students","tableData":[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 10:44:16 AM"},{"id":2,"name":"曹贵生","birthDay":"Jun 22, 2012 10:44:16 AM"},{"id":3,"name":"柳波","birthDay":"Jun 22, 2012 10:44:16 AM"}]},{"tableName":"teachers","tableData":[{"id":1,"name":"米老师","title":"教授"},{"id":2,"name":"丁老师","title":"讲师"}]}]
		// 对象转为Json-->end

		// /////////////////////////////////////////////////////////////////////

		// 将json转为数据-->start
		List<TableData> tableDatas2 = gson.fromJson(s,
				new TypeToken<List<TableData>>() {
				}.getType());
		for (int i = 0; i < tableDatas2.size(); i++) {
			TableData entityData = tableDatas2.get(i);
			String tableName = entityData.getTableName();
			List tableData = entityData.getTableData();
			String s2 = gson.toJson(tableData);
			// System.out.println(s2);
			// System.out.println(entityData.getData());
			if (tableName.equals("students")) {
				System.out.println("students");
				List<Student> retStuList = gson.fromJson(s2,
						new TypeToken<List<Student>>() {
						}.getType());
				for (int j = 0; j < retStuList.size(); j++) {
					System.out.println(retStuList.get(j));
				}

			} else if (tableName.equals("teachers")) {
				System.out.println("teachers");
				List<Teacher> retTchrList = gson.fromJson(s2,
						new TypeToken<List<Teacher>>() {
						}.getType());
				for (int j = 0; j < retTchrList.size(); j++) {
					System.out.println(retTchrList.get(j));
				}
			}
		}

		// Json转为对象-->end
	}
}

输出结果:

[{"tableName":"students","tableData":[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 10:04:12 PM"},{"id":2,"name":"曹贵生","birthDay":"Jun 22, 2012 10:04:12 PM"},{"id":3,"name":"柳波","birthDay":"Jun 22, 2012 10:04:12 PM"}]},{"tableName":"teachers","tableData":[{"id":1,"name":"米老师","title":"教授"},{"id":2,"name":"丁老师","title":"讲师"}]}]
students
Student [birthDay=Fri Jun 22 22:04:12 CST 2012, id=1, name=李坤]
Student [birthDay=Fri Jun 22 22:04:12 CST 2012, id=2, name=曹贵生]
Student [birthDay=Fri Jun 22 22:04:12 CST 2012, id=3, name=柳波]
teachers
Teacher [id=1, name=米老师, title=教授]
Teacher [id=2, name=丁老师, title=讲师]

实例代码下载: http://download.youkuaiyun.com/detail/lk_blog/4387822