总思路
总的工具要求底层完全可复用的代码全部提炼，也就是不通类型（GET, POST， DELETE, PUT 等等）请求的决定性公共步骤其实是可以提炼出来的。
即 一个请求，请求头一定会有，请求路径一定会有，发起请求一定会有，返回处理一定会有。
但同时由于请求头内容可能会有不同的要求或者加密方式，所以需要将相关加工过程放到基础工具类之外，保证调用基础工具类时只执行所有请求都需要的的步骤，不带有特殊处理。
这里主要使用的都是 org.apache.http 已包装的 httpClient ，项目中进一步将各种类型的请求做进一步提炼和封装。
从最底层开始说明
RestfulService
基础 RestfulService 工具代码可以参考如下：
个别说明加入到注释中或示例代码结尾
......
import org.apache.http.HttpEntity;
import org.apache.http.HttpHeaders;
import org.apache.http.NameValuePair;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpDelete;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpPut;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.URI;
import java.nio.charset.StandardCharsets;
import java.util.Objects;
public class MyRestfulService {
private static xxxLogger = new xxxLog(MyRestfulService .class);
// 所有请求都由 httpClient.execute() 方式发出
private CloseableHttpClient httpClient;
// 由于 httpClient 也存在自定义各种属性，所以这里也作为一个定义的参数
// 通过构造方法传入外侧定义的 CloseableHttpClient
public MyRestfulService(CloseableHttpClient client) {
this.httpClient = client;
}
// 一般的GET 请求
public String jsonGet(String url, final NameValuePair[] headerParams) throws IOException, XxxxException {
URI uri = URI.create(url);
HttpGet get = new HttpGet(uri);
this.addHeaders(headerParams, get);
CloseableHttpResponse response = httpClient.execute(get);
return this.parseResponseData(response, url);
}
// Get请求 获取文件某字符串开头的
public String fileGetLine(String url, final NameValuePair[] headerParams, String head) throws IOException,
XxxxException {
URI uri = URI.create(url);
HttpGet get = new HttpGet(uri);
this.addHeaders(headerParams, get);
CloseableHttpResponse response = httpClient.execute(get);
BufferedReader br = null;
try {
br = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "UTF-8"));
String output;
while ((output = br.readLine()) != null) {
if (output.contains(head) && Objects.equals(output.split("=")[0], head)) {
return output;
}
}
return null;
} catch (Exception e) {
logger.error("Failed to get rest response", e);
// 为自定义异常类型
throw new XxxxException(ExceptionType.XXXXXX);
} finally {
if (br != null) {
br.close();
}
response.close();
}
}
// 携带请求体即 Body 的GET 请求 其中 HttpGetWithEntity 需要自定义到文件中 稍后给出示例
public String jsonGetWithBody(String url, final NameValuePair[] headerParams, String requestBody)
throws IOException, XxxxException {
URI uri = URI.create(url);
HttpGetWithEntity get = new HttpGetWithEntity(uri);
this.addHeaders(headerParams, get);
StringEntity input = new StringEntity(requestBody, ContentType.APPLICATION_JSON);
get.setEntity(input);
CloseableHttpResponse response = httpClient.execute(get);
return this.parseResponseData(response, url);
}
// 普通的POST 请求
public String jsonPost(String url, final NameValuePair[] headerParams, String requestBody)
throws IOException, XxxxException {
HttpPost post = new HttpPost(url);
this.addHeaders(headerParams, post);
if (requestBody != null) {
StringEntity input = new StringEntity(requestBody, ContentType.APPLICATION_JSON);
post.setEntity(input);
}
CloseableHttpResponse response = httpClient.execute(post);
return this.parseResponseData(response, url);
}
// 普通 put 请求
public String jsonPut(String url, final NameValuePair[] headerParams, String requestBody)
throws IOException, XxxxException {
HttpPut put = new HttpPut(url);
this.addHeaders(headerParams, put);
StringEntity input = new StringEntity(requestBody, ContentType.APPLICATION_JSON);
put.setEntity(input);
CloseableHttpResponse response = httpClient.execute(put);
return this.parseResponseData(response, url);
}
// 一般的DELETE 请求
public String jsonDelete(String url, final NameValuePair[] headerParams) throws IOException, XxxxException {
HttpDelete delete = new HttpDelete(url);
this.addHeaders(headerParams, delete);
CloseableHttpResponse response = null;
response = httpClient.execute(delete);
return this.parseResponseData(response, url);
}
// 携带请求体的DELETE 请求 HttpDeleteWithBody
public String jsonDeleteWithBody(String url, final NameValuePair[] headerParams, String requestBody)
throws IOException, XxxxException {
HttpDeleteWithBody delete = new HttpDeleteWithBody(url);
this.addHeaders(headerParams, delete);
StringEntity input = new StringEntity(requestBody, ContentType.APPLICATION_JSON);
delete.setEntity(input);
CloseableHttpResponse response = null;
response = httpClient.execute(delete);
return this.parseResponseData(response, url);
}
// 文件类传入 上传
public String uploadFile(String url, final NameValuePair[] headerParams, HttpEntity multipartEntity)
throws IOException, XxxxException {
HttpPost post = new HttpPost(url);
post.setEntity(multipartEntity);
post.addHeader(HttpHeaders.CONTENT_TYPE, post.getEntity().getContentType().getValue());
if (headerParams != null) {
for (NameValuePair nameValuePair : headerParams) {
post.addHeader(nameValuePair.getName(), nameValuePair.getValue());
}
}
return this.parseResponseData(httpClient.execute(post), url);
}
// 数据结果转换
private String parseResponseData(CloseableHttpResponse response, String url) throws IOException,
XxxxException {
BufferedReader br = null;
try {
// 编码转义结果
br = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), StandardCharsets.UTF_8));
StringBuilder sbuilder = new StringBuilder();
String output;
while ((output = br.readLine()) != null) {
sbuilder.append(output);
}
logger.debug("MyRestfulService Request-URL: " url "; response: " response.toString() "; data:" sbuilder "}");
int statusCode = response.getStatusLine().getStatusCode();
// 200 可用已有常量替代 HTTP 本身有提供
if (statusCode != 200) {
logger.info("Failed to get restful response, http error code = " statusCode);
}
return sbuilder.toString();
} catch (Exception e) {
logger.error("Failed to get rest response", e);
// 自定义异常
throw new XxxxException(ExceptionType.XXXXXXX);
} finally {
if (br != null) {
br.close();
}
response.close();
}
}
// 公用 添加自定义请求头信息
private void addHeaders(final NameValuePair[] headerParams, HttpRequestBase requestBase) {
if (headerParams != null) {
for (int i = 0; i < headerParams.length; i ) {
NameValuePair nameValuePair = headerParams[i];
requestBase.addHeader(nameValuePair.getName(), nameValuePair.getValue());
}
}
this.addCommonHeader(requestBase);
}
// 公用 添加公共请求头或公共操作
private void addCommonHeader(HttpRequestBase method) {
// 去除个别属性
if (method.containsHeader("Content-Length")) {
method.removeHeaders("Content-Length");
}
// 没有则添加
if (!method.containsHeader("Content-Type")) {
method.addHeader("Content-Type", "application/json;charset=utf-8");
}
// 强制更新或添加
method.setHeader("accept", "application/json,text/plain,text/html");
}
// 文件下载
public String downloadFile(String url, OutputStream outputStream,NameValuePair[] headerParams)
throws IOException, DXPException {
HttpGet httpget = new HttpGet(url);
this.addHeaders(headerParams, httpget);
CloseableHttpResponse execute = httpClient.execute(httpget);
if(null != execute && execute.containsHeader("Content-Disposition")){
HttpEntity entity = execute.getEntity();
if (entity != null ) {
entity.writeTo(outputStream);
}
}else {
return this.parseResponseData(execute, url);
}
return null;
}
// httpClient 对应的get set 方法
public CloseableHttpClient getHttpClient() {
return this.httpClient;
}
public void setHttpClient(CloseableHttpClient httpClient) {
this.httpClient = httpClient;
}
}上面
HttpDeleteWithBody 定义：
import java.net.URI;
import org.apache.http.client.methods.HttpEntityEnclosingRequestBase;
public class HttpDeleteWithBody extends HttpEntityEnclosingRequestBase {
public static final String METHOD_NAME = "DELETE";
public HttpDeleteWithBody(final String uri) {
super();
setURI(URI.create(uri));
}
public HttpDeleteWithBody(final URI uri) {
super();
setURI(uri);
}
public HttpDeleteWithBody() {
super();
}
public String getMethod() {
return METHOD_NAME;
}
}上面 HttpGetWithBody:
import org.apache.http.client.methods.HttpEntityEnclosingRequestBase;
public class HttpGetWithEntity extends HttpEntityEnclosingRequestBase {
private static final String METHOD_NAME = "GET";
public HttpGetWithEntity() {
super();
}
public HttpGetWithEntity(final URI uri) {
super();
setURI(uri);
}
HttpGetWithEntity(final String uri) {
super();
setURI(URI.create(uri));
}
@Override
public String getMethod() {
return METHOD_NAME;
}
}具体来源其实就是照抄 源码 httppost POST 的结构
然后换个名字以及属性名即可完成请求体的携带
NameValuePair[]
示例中用到了大量的 NameValuePair[] 其，内部结构类似于 Map 但内部属性为name, value。
实际也可以使用 Map 来替代这种存储结构， NameValuePair 也是 org.apache.http 内部提供的类。
工具类上一层
其他调用者。用于处理特殊的请求头信息，拼接请求参数以及请求路径等内容
并构建使用的 CloseableHttpClient 传入工具类。
示例：
某一 上层 Service 的内容示例：
......
......
import org.apache.commons.lang.StringUtils;
import org.apache.http.HttpHeaders;
import org.apache.http.NameValuePair;
import org.apache.http.client.config.AuthSchemes;
import org.apache.http.client.config.CookieSpecs;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.HttpDelete;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.config.ConnectionConfig;
import org.apache.http.config.SocketConfig;
import org.apache.http.conn.ssl.NoopHostnameVerifier;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.message.BasicNameValuePair;
import org.springframework.stereotype.Service;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
@Service("XXXRestfulService")
public class XXXRestfulService implements IXxxRestfulService {
private static final XXXLog xxxLog = new XXXLog(XXXRestfulService .class);
private static int maxConnPerHost = 20;
private static int maxTotalConn = 20;
/**
* 数据读取超时时间
*/
private static int soTimeout = 30000;
/**
* http连接超时时间
*/
private static int connectionTimeout = 10000;
/**
* 连接管理器超时时间
*/
private static int connectionManagerTimeout = 10000;
// 基础工具类对象声明
private MyRestfulService restService;
private CloseableHttpClient createHttpClient() {
CloseableHttpClient httpClient = null;
try {
@SuppressWarnings("deprecation") ConnectionConfig cConfig =
ConnectionConfig.custom().setCharset(StandardCharsets.UTF_8).build();
SocketConfig config = SocketConfig.custom().setSoTimeout(soTimeout).build();
RequestConfig defaultRequestConfig =
RequestConfig.custom().setExpectContinueEnabled(true).setCookieSpec(CookieSpecs.DEFAULT)
.setTargetPreferredAuthSchemes(Arrays.asList(AuthSchemes.NTLM, AuthSchemes.DIGEST))
.setProxyPreferredAuthSchemes(Arrays.asList(AuthSchemes.BASIC))
.setConnectionRequestTimeout(connectionManagerTimeout).setConnectTimeout(connectionTimeout)
.setSocketTimeout(soTimeout).build();
httpClient = HttpClientBuilder.create().setMaxConnPerRoute(maxConnPerHost).setMaxConnTotal(maxTotalConn)
.setSSLHostnameVerifier(new NoopHostnameVerifier())
.setDefaultRequestConfig(RequestConfig.copy(defaultRequestConfig).build())
.setDefaultConnectionConfig(cConfig).setDefaultSocketConfig(config).build();
} catch (Exception e) {
xxxLog.error("Create Http Client Failed", e);
}
return httpClient;
}
// 类初始化时执行的方法
@PostConstruct
public void initProperties() {
try {
CloseableHttpClient client = this.createHttpClient();
this.restService = new MyRestfulService(client);
} catch (Exception e) {
xxxLog.error("Failed To Init DataFillRestfulService", e);
}
}
// 关闭资源，如果每次都重新请求则也可以放到工具类内每次请求完成都关闭
@PreDestroy // @PreDestroy 实际 Servlet 被销毁前调用的方法
public void destroy() {
try {
CloseableHttpClient httpclient = restService.getHttpClient();
httpclient.close();
} catch (IOException e) {
xxxLog.error("Failed To Destroy HttpClient", e);
}
}
// 对请求头内容的特殊处理
private NameValuePair[] getBaseHeaders(String methodName, String urlStr) {
// 对请求头内容的特殊处理 若没有则直接添加到 返回值 NameValuePair[] 数组即可
............
}
// 如果需要URL编码则可以使用该方法
private String encodeHeader(String value) throws UnsupportedEncodingException {
if (StringUtils.isEmpty(value)) {
return value;
}
return URLEncoder.encode(value, "UTF-8");
}
// 拼接实际请求路径
// XXXXConfig 可以作为一个类专门加载配置文件中的一些有关的地址信息等
public String getRequestUrl(String actionUrl) {
return XXXXConfig.getXxxxServer() actionUrl;
}
@Override
public String get(final String actionUrl, Map<String, String> map) {
String requestUrl = getRequestUrl(actionUrl);
// 传入实际地址等 调用基础工具类请求
.....
}
@Override
public String post(final String actionUrl, final String jsonBody) {
String requestUrl = getRequestUrl(actionUrl);
// 传入实际地址等 调用基础工具类请求
.....
}
@Override
public String delete(final String actionUrl) {
String requestUrl = getRequestUrl(actionUrl);
// 传入实际地址等 调用基础工具类请求
.....
}
}
可以看的出，上层工具类先声明了 工具类对象 然后在当前类初始化时完成了对当前Service请求自己 httpClient 的相关创建以及配置的赋值，并将该对象 传递给工具类，使得调用工具类时依旧使用的是自己创建的那一个对象。
并通过一般的工具类将需要的配置文件的信息加载后，直接在该类中引用。完成请求信息的拼接。
由于不同的产品间的请求头要求信息可能不同，所以需要自己额外处理请求头相关信息。
这里其实还是在封装部分内容，使得业务请求调用时进一步简化。
一些工具类特殊的传入如下示例：
文件上传方式
public String uploadFile(String url, final NameValuePair[] headerParams, HttpEntity multipartEntity)
中 HttpEntity 中加入文件的方式
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);
builder.setCharset(StandardCharsets.UTF_8);
builder.addBinaryBody("file", inputStream, ContentType.DEFAULT_BINARY, fileName);
builder.build(); // 最终可以到的 想要的 HttpEntity 携带文件内容其中 inputStream 为 InputStream 类型的文件输入流， fileName 为 String 文件名；
获取文件流
public String downloadFile(String url, OutputStream outputStream,NameValuePair[] headerParams)
获得请求中的文件流，则需要传入 OutputStream 类型的 输出流对象 outputStream。
再上一层的业务调用
业务层处则通过直接定义指定的方法和入参，在内部直接写入请求映射路径，并要求传入指定参数完成业务封装，类似于：
@Override
public XxxxxxxDTO<XXX> getXxxxList(XxxxxListRequest request,
String xxx, String xxxx) throws XXXException {
String url = "/xxxx/api/xxxx/xxxx/list";
String result = XxxxxRestfulService.post(url, JsonUtil.getJsonStr(request), xxx, xxxx);
// 对 result 进行转化 转为自定义类或者Map 等返回
return ......;
}这样在外部调用该业务方法时需要感知的只有入参，其他几乎感知不到，与一般的方法差别几乎没有
以上为个人经验，希望能给大家一个参考，也希望大家多多支持Devmax。