RestTemplate是什么
- 传统情况下在java代码里访问restful服务，一般使用Apache的HttpClient。不过此种方法使用起来太过繁琐。spring提供了一种简单便捷的模板类来进行操作，这就是RestTemplate。
封装使用
import com.example.demo.controllers.IndexController;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.*;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestTemplate;
import java.io.*;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.zip.GZIPInputStream;
/**
* http请求公共类
*/
public class ResponseResule {
private static final Logger logger = LoggerFactory.getLogger(IndexController.class);
/**
* 请求接口公共方法
* @param Methods
* @param url
* @param UrlParams
* @return
*/
public static String getResponse(String url, HttpMethod Methods, Map<String, String> UrlParams, Map<String, String> HeaderParams) throws IOException {
RestTemplate client = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
HttpMethod method = Methods;
// 以表单的方式提交
headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
// 设置用户提交的header头数据
if (!HeaderParams.isEmpty()) {
HeaderParams.forEach((k, v) -> {
headers.set(k, v);
});
}
// 将请求头部和参数合成一个请求
MultiValueMap<String, String> params = new LinkedMultiValueMap<>();
if (Methods == HttpMethod.GET) {
String _UrlParams = getUrlParamsByMap(UrlParams);
url = url + "?" +_UrlParams;
}else {
if (!UrlParams.isEmpty()) {
UrlParams.forEach((k,v) ->{
params.put(k, Collections.singletonList(v));
});
}
}
// logger.info("URL:{}", url);
HttpEntity<MultiValueMap<String, String>> requestEntity = new HttpEntity<>(params, headers);
// 执行HTTP请求，将返回的结构使用spring ResponseEntity处理http响应
ResponseEntity<byte[]> responseEntity = client.exchange(url, method, requestEntity, byte[].class);
String contentEncoding = responseEntity.getHeaders().getFirst(HttpHeaders.CONTENT_ENCODING);
// gzip编码
if ("gzip".equals(contentEncoding)) {
// gzip解压服务器的响应体
byte[] data = unGZip(new ByteArrayInputStream(responseEntity.getBody()));
// logger.info(new String(data, StandardCharsets.UTF_8));
return new String(data);
} else {
// 其他编码暂时不做处理(如果需要处理其他编码请自行扩展)
return new String(responseEntity.getBody());
}
}
/**
* Gzip解压缩
* @param inputStream
* @return
* @throws IOException
*/
public static byte[] unGZip(InputStream inputStream) throws IOException {
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
try (GZIPInputStream gzipInputStream = new GZIPInputStream(inputStream)) {
byte[] buf = new byte[4096];
int len = -1;
while ((len = gzipInputStream.read(buf, 0, buf.length)) != -1) {
byteArrayOutputStream.write(buf, 0, len);
}
return byteArrayOutputStream.toByteArray();
} finally {
byteArrayOutputStream.close();
}
}
/**
* 把数组所有元素排序，并按照“参数=参数值”的模式用“&”字符拼接成字符串
* @param params 需要排序并参与字符拼接的参数组
* @return 拼接后字符串
* @throws UnsupportedEncodingException
*/
public static String getUrlParamsByMap(Map<String, String> params) throws UnsupportedEncodingException {
List<String> keys = new ArrayList<String>(params.keySet());
Collections.sort(keys);
String prestr = "";
for (int i = 0; i < keys.size(); i++) {
String key = keys.get(i);
String value = params.get(key);
value = URLEncoder.encode(value, "UTF-8");
if (i == keys.size() - 1) {//拼接时，不包括最后一个&字符
prestr = prestr + key + "=" + value;
} else {
prestr = prestr + key + "=" + value + "&";
}
}
return prestr;
}
}
使用方法
String url = "http://192.168.1.115:8621/test";
// 设置参数
String username = "admin";
Map<String, String> params = new HashMap<>();
params.put("username", username);
// 设置Header头数据
Map<String, String> HeaderParams = new HashMap<>();
// HttpMethod.POST / HttpMethod.GET
String result = ResponseResule.getResponse(url, HttpMethod.POST, params, HeaderParams);
System.out.println(result); // 返回json字符串数据
