Java使用Gson生成json数据

Gson介绍：

Gson 是 Google 提供的用来在 Java 对象和 JSON 数据之间进行映射的 Java 类库。可以将一个 JSON 字符串转成一个 Java 对象，或者反过来。

示例代码：

Gson gson = new Gson();
int[] ints = {1, 2, 3, 4, 5};
String[] strings = {"a", "b", "c"};

(Serialization)
gson.toJson(ints);     ==> prints [1,2,3,4,5]
gson.toJson(strings);  ==> prints ["a", "b", "c"]

下载地址

下载完成需要进行jar包导入;

实例：

工具类 用来生成json格式数据

public class JsonTools {
	/**
	 * 使用Gson生成json数据
	 * @param object
	 * @return
	 */
	public static String createJson(Object object){
		Gson gson = new Gson();
		return gson.toJson(object);
	}
}

public class Service {
	/**
	 * 返回一个Person
	 * @return
	 */
	public  Person getPerson() {
		Person person = new Person();
		person.setId(1);
		person.setName("aa");
		person.setAddress("beij");
		return person;
	}
	/**
	 * 返回一组person
	 * @return
	 */
	public List<Person> getPersons(){
		List<Person> persons = new ArrayList<Person>();
		Person person1 = new Person(2,"bb","tianjin");
		Person person2 = new Person(3,"cc","beijing");
		persons.add(person1);
		persons.add(person2);
		return persons;
	}
	/**
	 * 返回 List 里面放入Map map里放入person
	 * @return
	 */
	public List<Map<String, Object>> getListMap(){
		List<Map<String, Object>> list = new ArrayList<Map<String,Object>>();
		Map<String, Object> map1 = new HashMap<String, Object>();
		map1.put("id", "01");
		map1.put("name", "01");
		map1.put("address", "01");
		
		Map<String, Object> map2 = new HashMap<String, Object>();
		map2.put("id", "02");
		map2.put("name", "032");
		map2.put("address", "31");
		list.add(map1);
		list.add(map2);
		return list;
	}
	public List<String> getListStr(){
		List<String> list = new ArrayList<String>();
		list.add("a");
		list.add("b");
		return list;
	}
}

单元测试 

public class JsonTest {
	@Test
	public void testJson(){
		String jsonStr = JsonTools.createJson(new Service().getPerson());
		System.out.println(jsonStr);
	}
	
	@Test
	public void testPersons(){
		Service service = new Service();
		String str = JsonTools.createJson(service.getPersons());
		System.out.println(str);
	}
	@Test
	public void testListMap(){
		Service service = new Service();
		String str = JsonTools.createJson(service.getListMap());
		System.out.println(str);
	}
	@Test
	public void testListStr(){
		Service service = new Service();
		String str = JsonTools.createJson(service.getListStr());
		System.out.println(str);
	}
}

运行结果

testJson()

{"id":1,"name":"aa","address":"beij"}

testPersons()

[{"id":2,"name":"bb","address":"tianjin"},{"id":3,"name":"cc","address":"beijing"}]

testListmap()

[{"id":"01","address":"01","name":"01"},{"id":"02","address":"31","name":"032"}]

testListStr()

["a","b"]

Servlet 响应：

部署到tomcat服务器下，配置web.xml文件来实现多个请求公用一个servlet 请求

方法：1.修改url-pattern

<servlet-mapping>
    <servlet-name>JsonAction</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>

2.在servlet中编写代码

public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html");
		response.setCharacterEncoding("utf-8");
		request.setCharacterEncoding("utf-8");
		// 获取servlet路径名称
		String servletPath = request.getServletPath();
		// 获取方法
		String methodName = servletPath.substring(1);
		methodName = methodName.substring(0, methodName.length() - 3);
		try {
			Method method = getClass().getDeclaredMethod(methodName,
					HttpServletRequest.class, HttpServletResponse.class);
			method.invoke(this, request, response);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

/**
	 * 得到一个person
	 * @param request
	 * @param response
	 */
	private void getPerson(HttpServletRequest request,HttpServletResponse response){
		
		try {
			PrintWriter out = response.getWriter();
			out.println(JsonTools.createJson(service.getPerson()));
			out.flush();
			out.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	/**
	 * 得到一组psrson
	 * @param request
	 * @param response
	 */
	private void getPersons(HttpServletRequest request,HttpServletResponse response){
		try {
			PrintWriter out = response.getWriter();
			out.println(JsonTools.createJson(service.getPersons()));
			out.flush();
			out.close();
		} catch (Exception e) {
			// TODO: handle exception
		}
	}
	private void getListMap(HttpServletRequest request,HttpServletResponse response){
		try {
			PrintWriter out = response.getWriter();
			out.println(JsonTools.createJson(service.getListMap()));
			out.flush();
			out.close();
		} catch (Exception e) {
			// TODO: handle exception
		}
	}
	private void getListStr(HttpServletRequest request,HttpServletResponse response){
		try {
			PrintWriter out = response.getWriter();
			out.println(JsonTools.createJson(service.getListStr()));
			out.flush();
			out.close();
		} catch (Exception e) {
			// TODO: handle exception
		}
	}
	
	
	//初始化
	public void init() throws ServletException {
		service = new Service();
	}

实现如下效果

这样就可以用客户端请求网址，得到josn数据，在进行json解析操作

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