使用Http客户端工具实现Json数据与对象的转换
作者：互联网
1、创建HttpGet请求,在请求里传入url。
HttpGet request = new HttpGet("http://localhost:xx/xx");
2.获取Json数据。使用CloseableHttpClient 对象，调用其execute()方法，传入HttpGet对象和BasicResponseHandler对象。
String response = this.httpClient.execute(request, new BiBasicResponseHandler());
3.使用ObjectMapper对象处理Json。
3.1 简单转换（转换不了集合类型）：
使用ObjectMapper对象，调用其readValue()方法，传入Json数据和需要转换的类的字节码对象。
User user = mapper.readValue(response, User.class);
3.2 复杂转换（处理复杂类型List<User>）：
使用ObjectMappper对象获取类型工厂getFactory()，并调用构造集合类型函数constructCollectionType("集合类型","目标类"),分别传入集合和目标类的字节码对象。
使用ObjectMapper对象，调用其readValue()方法，传入Json数据和构造集合类型。
List<User> users = mapper.readValue(response, mapper.getFactory().constructCollectionType(List.Class, User.class));
3.3 万能转换（能处理一切类型，包括集合中嵌套集合的类型）：
使用ObjectMapper对象调用其readValue()方法，传入Json数据和TypeReference<List<User>>()对象并指定泛型。
List<User> users = mapper.readValue(response, new TypeReference<List<User>>() { });
代码:
public class HttpTests {
CloseableHttpClient httpClient;
// 处理json
ObjectMapper mapper = new ObjectMapper();
@Before
public void init() {
// 创建httpClient的客户端
httpClient = HttpClients.createDefault();
}
@Test
public void testGet() throws IOException {
// 发起get请求
HttpGet request = new HttpGet("http://www.baidu.com");
// 执行请求
String response = this.httpClient.execute(request, new BasicResponseHandler());
System.out.println(response);
}
@Test
public void testPost() throws IOException {
/* HttpGet request = new
HttpGet("http://www.oschina.net/");*/
HttpPost request = new HttpPost("http://www.oschina.net/");
request.setHeader("User-Agent",
"Mozilla/5.0 (Windows NT 6.1)
AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.72 Safari/537.36");
String response = this.httpClient.execute(request, new BasicResponseHandler());
System.out.println(response);
}
@Test
public void testGetPojo() throws IOException {
HttpGet request = new HttpGet("http://localhost:33/list");
// 获取JSON数据
String response = this.httpClient.execute(request, new BasicResponseHandler());
// 处理JSON,转简单类型，集合类型转不了
/*User user = mapper.readValue(response,
User.class);*/
// 处理复杂类型List<User>
// 使用ObjectMapper对象获取类型工厂getTypeFactory()
//List<User> users =
mapper.readValue(response,
mapper.getTypeFactory().constructCollectionType(List.class, User.class));
// 处理一切类型，包括集合中嵌套集合的类型
List<User> users = mapper.readValue(response, new TypeReference<List<User>>()
{});
for (User user: users) {
System.out.println(user);
}
// System.out.println(users);
}
}
POM依赖文件:
<name>http-demo</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.1.RELEASE</version>
<relativePath/><!-- lookup parent from repository
-->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.1</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
使用ObjectMapper对象获取类型工厂getTypeFactory()并调用构造集合类型函数constructCollectionType(“集合类型”,”目标类”)，分别传入集合和目标类的字节码对象。使用ObjectMapper对象，调用其readValue()方法，传入Json数据和构造好的集合类型。
标签：mapper,HttpGet,Http,readValue,request,Json,new,response,客户端 来源： https://www.cnblogs.com/sfwu/p/16489345.html