SpringMVC的Controller接受参数适配

SpringMVC的Controller接受参数适配
•发布于 •作者 liuzy •1012 次浏览 •最后一次编辑是 •来自技术

**在使用Controller直接接受Bean作为传入参数时，经常遇到服务器415错误。**

**为总结经验，我使用HttpURLConnection向SpringMVC项目接口发起请求，测试Controller接受参数的情况**

**测试过程如下，你也可以直接跳到最后总结。**

**SpringMvc的部分配置，我给Spring配置的是FastJson转换器。因为它可以配置一些参数，例如把Null转为""。**
```

<mvc:annotation-driven>
	<mvc:message-converters register-defaults="true">
		<bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
			<property name="features">
				<array>
					
					<value>WriteMapNullValue</value>
					
					
					
					<value>WriteNullNumberAsZero</value>
					
					<value>WriteNullBooleanAsFalse</value>
					
					<value>WriteNullStringAsEmpty</value>
				</array>
			</property>
		</bean>
	</mvc:message-converters>
</mvc:annotation-driven>
```

**接受请求的Controller代码如下**
```
@Controller
@RequestMapping("/test")
public class Test {
	@RequestMapping("/one")
	@ResponseBody
	public Object one(String u, String p) {
		Vo vo = new Vo(u, p);
		System.out.println("one: " + vo);
		return vo;
	}
	@RequestMapping("/two")
	@ResponseBody
	public Object two(@RequestParam(required = false) String u, @RequestParam(required = false) String p) {
		Vo vo = new Vo(u, p);
		System.out.println("two: " + vo);
		return vo;
	}
	@RequestMapping("/three")
	@ResponseBody
	public Object three(@RequestBody(required = false) String u, @RequestBody(required = false) String p) {
		Vo vo = new Vo(u, p);
		System.out.println("three: " + vo);
		return vo;
	}
	@RequestMapping("/four")
	@ResponseBody
	public Object four(@RequestBody(required = false) Vo vo) {
		System.out.println("four: " + vo);
		return vo;
	}
}
```

**发起请求的类HttpClient代码如下**
```
public class HttpClient {
	public static void main(String[] args) {
		HttpClient client = new HttpClient();
		String one = "http://127.0.0.1/test/one";
		String two = "http://127.0.0.1/test/two";
		String three = "http://127.0.0.1/test/three";
		String four = "http://127.0.0.1/test/four";
//		client.put2url("u", "liuzy").put("p", "111111");
//		client.put2body("u", "liuzy").put("p", "111111");
//		client.setBodyType("json");
//		client.put2header("Content-Type", "application/json");
		client.doGET(one);
		client.doGET(two);
		client.doGET(three);
		client.doGET(four);
		client.doPOST(one);
		client.doPOST(two);
		client.doPOST(three);
		client.doPOST(four);
	}
	private static void log(String msg) {
		System.out.println(msg);
	}
	private String bodyType = "kvStr";
	private Map<String, String> urlParams = new HashMap<>();
	private Map<String, String> bodyParams = new HashMap<>();
	private Map<String, String> headerParams = new HashMap<>();
	public Map<String, String> put2url(String key, String value) {
		urlParams.put(key, value);
		return urlParams;
	}
	public Map<String, String> put2body(String key, String value) {
		bodyParams.put(key, value);
		return bodyParams;
	}
	public Map<String, String> put2header(String key, String value) {
		headerParams.put(key, value);
		return headerParams;
	}
	public void setBodyType(String bodyType) {
		this.bodyType = bodyType; 
	}
	public String doGET(String url) {
		return request(url, "GET");
	}
	public String doPOST(String url) {
		return request(url, "POST");
	}
	public String request(String url, String method) {
		log(url);
		String result = "";
		try {
			url = addUrlParams(url);
			URL uri = new URL(url);
			HttpURLConnection conn = (HttpURLConnection) uri.openConnection();
			conn.setRequestMethod(method);
			conn.setConnectTimeout(5000);
			conn.setReadTimeout(5000);
			addHeaderParams(conn);
			addBodyParams(conn);
			InputStream inputStream = conn.getInputStream();
			result = readStream(inputStream);
		} catch (Exception e) {
			e.printStackTrace();
		}
		log(result);
		return result;
	}
	private String addUrlParams(String url) {
		if (urlParams.isEmpty())
			return url;
		StringBuilder sb = new StringBuilder();
		if (!url.contains("?"))
			sb.append("?");
		for (String key : urlParams.keySet()) {
			sb.append(key).append("=").append(urlParams.get(key)).append("&");
		}
		return url + sb.substring(0, sb.length() - 1);
	}
	private void addBodyParams(HttpURLConnection conn) {
		try {
			conn.setDoOutput(true);
			OutputStream outputStream = conn.getOutputStream();
			if ("json".equals(bodyType)) {
				String json = toJson(bodyParams);
				outputStream.write(json.getBytes());
			} else {
				String kvStr = toKvStr(bodyParams);
				outputStream.write(kvStr.getBytes());
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	private void addHeaderParams(HttpURLConnection conn) {
		for (String key : headerParams.keySet())
			conn.addRequestProperty(key, headerParams.get(key));
	}
	private String toJson(Map<String, String> params) {
		StringBuilder json = new StringBuilder("{");
		for (String key : params.keySet()) {
			json.append("\"").append(key).append("\":\"").append(params.get(key)).append("\",");
		}
		return json.substring(0, json.length() - 1) + "}";
	}
	private String toKvStr(Map<String, String> params) {
		StringBuilder sb = new StringBuilder();
		for (String key : params.keySet()) {
			sb.append(key).append("=").append(params.get(key)).append("&");
		}
		return sb.substring(0, sb.length() - 1);
	}
	private String readStream(InputStream inputStream) throws Exception {
		ByteArrayOutputStream outSteam = new ByteArrayOutputStream();
		byte[] buffer = new byte[1024];
		int len = -1;
		while ((len = inputStream.read(buffer)) != -1) {
			outSteam.write(buffer, 0, len);
		}
		outSteam.close();
		inputStream.close();
		return new String(outSteam.toByteArray(), "UTF-8");
	}
}
```

**测试开始**

**测试1**
`client.put2url("u", "liuzy").put("p", "111111");`
doGET		one			成功
doGET		two			成功
doGET		three		空
doGET		four		报错
doPOST		one			成功
doPOST		two			成功
doPOST		three		空
doPOST		four		报错

**测试2**
`client.put2body("u", "liuzy").put("p", "111111");`
doGET		one			成功
doGET		two			成功
doGET		three		错误的结果
doGET		four		报错
doPOST		one			成功
doPOST		two			成功
doPOST		three		错误的结果
doPOST		four		报错

**测试3**
`client.put2body("u", "liuzy").put("p", "111111");`
`client.setBodyType("json");`
doGET		one			空
doGET		two			空
doGET		three		错误的结果
doGET		four		报错
doPOST		one			空
doPOST		two			空
doPOST		three		错误的结果
doPOST		four		报错

**测试4**
`client.put2body("u", "liuzy").put("p", "111111");`
`client.setBodyType("json");`
`client.put2header("Content-Type", "application/json");`
doGET		one			空
doGET		two			空
doGET		three		错误的结果
doGET		four		成功
doPOST		one			空
doPOST		two			空
doPOST		three		错误的结果
doPOST		four		成功

**总结**
1、url参数是地址栏中，以&连接的kv字符串。
2、body参数是以流的方式写入以&连接的kv字符串（使用,连接转换器也能识别）。
3、在body中以流的方式写入json字符串时，如果没有header中设置类型为json，服务器拿到的是%7B%22u%22%3A%22liuzy%22%2C%22p%22%3A%22111111%22%7D=，他认为是kv，不能转为对象。
4、Controller的参数默认从url中的kv参数和body中的kv参数中取。
5、从Controller的日志可以看出，通常只需要一个@RequestBody就行了。

** ^_^ **

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liuzy

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SonarQube 9.4 + PostgreSQL

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