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引言

??在代碼開發(fā)過程中，發(fā)現(xiàn)很多地方通過RestTemplate調(diào)用了第三方接口，而第三方接口需要根據(jù)某些狀態(tài)碼或者異常進(jìn)行重試調(diào)用，此時(shí)，要么在每個(gè)調(diào)用的地方進(jìn)行異常捕獲，然后重試；要么在封裝的RestTemplate工具類中進(jìn)行統(tǒng)一異常捕獲和封裝。當(dāng)然，本文不走尋常路，將會(huì)通過RestTemplate的異常處理器進(jìn)行操作。文章來源地址http://www.zghlxwxcb.cn/news/detail-654719.html

RestTemplate異常處理器介紹

分類

RestTemplate異常處理器源碼

ResponseErrorHandler

public interface ResponseErrorHandler {
	/**
	 * 判斷請(qǐng)求是否異常
	 * false: 請(qǐng)求返回?zé)o錯(cuò)誤
	 * true: 請(qǐng)求返回有錯(cuò)誤
	 * 可定制化根據(jù)某一些status的值進(jìn)行返回，如根據(jù)2xx返回false，非2xx返回true
	 * 同時(shí)，可根據(jù)ClientHttpResponse的返回結(jié)果來定制化判斷
	 */
    boolean hasError(ClientHttpResponse var1) throws IOException;
	/**
	 * 處理錯(cuò)誤
	 */
    void handleError(ClientHttpResponse var1) throws IOException;
	/**
	 * 默認(rèn)的異常處理方法
	 */
    default void handleError(URI url, HttpMethod method, ClientHttpResponse response) throws IOException {
    	//默認(rèn)調(diào)用handleError(response)方法，也可以重寫該方法
        this.handleError(response);
    }
}

DefaultResponseErrorHandler

package org.springframework.web.client;

import java.io.IOException;
import java.nio.charset.Charset;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.HttpStatus.Series;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.lang.Nullable;
import org.springframework.util.FileCopyUtils;

public class DefaultResponseErrorHandler implements ResponseErrorHandler {
    public DefaultResponseErrorHandler() {
    }
	/**
	 * 判斷請(qǐng)求是否異常
	 */
    public boolean hasError(ClientHttpResponse response) throws IOException {
        HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
        //statusCode不為空并調(diào)用受保護(hù)的方法hasError()方法
        return statusCode != null && this.hasError(statusCode);
    }

    protected boolean hasError(HttpStatus statusCode) {
    	//遇到客戶端錯(cuò)誤4xx或服務(wù)端錯(cuò)誤5xx，就返回true表示有錯(cuò)誤
        return statusCode.series() == Series.CLIENT_ERROR || statusCode.series() == Series.SERVER_ERROR;
    }
	/**
	 * 處理錯(cuò)誤
	 */
    public void handleError(ClientHttpResponse response) throws IOException {
    	//獲取狀態(tài)碼
        HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
        if (statusCode == null) {
            throw new UnknownHttpStatusCodeException(response.getRawStatusCode(), response.getStatusText(), response.getHeaders(), this.getResponseBody(response), this.getCharset(response));
        } else {
        	//狀態(tài)碼不為空，則處理錯(cuò)誤（主要是4xx和5xx錯(cuò)誤）
            this.handleError(response, statusCode);
        }
    }
	/**
	 * 處理錯(cuò)誤
	 */
    protected void handleError(ClientHttpResponse response, HttpStatus statusCode) throws IOException {
        String statusText = response.getStatusText();
        HttpHeaders headers = response.getHeaders();
        byte[] body = this.getResponseBody(response);
        Charset charset = this.getCharset(response);
        switch(statusCode.series()) {
        case CLIENT_ERROR:
        	//http客戶端錯(cuò)誤
            throw HttpClientErrorException.create(statusCode, statusText, headers, body, charset);
        case SERVER_ERROR:
        	//http服務(wù)端錯(cuò)誤
            throw HttpServerErrorException.create(statusCode, statusText, headers, body, charset);
        default:
            throw new UnknownHttpStatusCodeException(statusCode.value(), statusText, headers, body, charset);
        }
    }

    /** @deprecated */
    @Deprecated
    protected HttpStatus getHttpStatusCode(ClientHttpResponse response) throws IOException {
        HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
        if (statusCode == null) {
            throw new UnknownHttpStatusCodeException(response.getRawStatusCode(), response.getStatusText(), response.getHeaders(), this.getResponseBody(response), this.getCharset(response));
        } else {
            return statusCode;
        }
    }

    protected byte[] getResponseBody(ClientHttpResponse response) {
        try {
            return FileCopyUtils.copyToByteArray(response.getBody());
        } catch (IOException var3) {
            return new byte[0];
        }
    }

    @Nullable
    protected Charset getCharset(ClientHttpResponse response) {
        HttpHeaders headers = response.getHeaders();
        MediaType contentType = headers.getContentType();
        return contentType != null ? contentType.getCharset() : null;
    }
}

ExtractingResponseErrorHandler

package org.springframework.web.client;

import java.io.IOException;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import org.springframework.http.HttpStatus;
import org.springframework.http.HttpStatus.Series;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.lang.Nullable;
import org.springframework.util.CollectionUtils;

public class ExtractingResponseErrorHandler extends DefaultResponseErrorHandler {
	//定義HttpMessageConverter對(duì)象列表
    private List<HttpMessageConverter<?>> messageConverters = Collections.emptyList();
    private final Map<HttpStatus, Class<? extends RestClientException>> statusMapping = new LinkedHashMap();
    private final Map<Series, Class<? extends RestClientException>> seriesMapping = new LinkedHashMap();

    public ExtractingResponseErrorHandler() {
    }

    public ExtractingResponseErrorHandler(List<HttpMessageConverter<?>> messageConverters) {
        this.messageConverters = messageConverters;
    }

    public void setMessageConverters(List<HttpMessageConverter<?>> messageConverters) {
        this.messageConverters = messageConverters;
    }

    public void setStatusMapping(Map<HttpStatus, Class<? extends RestClientException>> statusMapping) {
        if (!CollectionUtils.isEmpty(statusMapping)) {
            this.statusMapping.putAll(statusMapping);
        }

    }

    public void setSeriesMapping(Map<Series, Class<? extends RestClientException>> seriesMapping) {
        if (!CollectionUtils.isEmpty(seriesMapping)) {
            this.seriesMapping.putAll(seriesMapping);
        }

    }

    protected boolean hasError(HttpStatus statusCode) {
        if (this.statusMapping.containsKey(statusCode)) {
            return this.statusMapping.get(statusCode) != null;
        } else if (this.seriesMapping.containsKey(statusCode.series())) {
            return this.seriesMapping.get(statusCode.series()) != null;
        } else {
            return super.hasError(statusCode);
        }
    }

    public void handleError(ClientHttpResponse response, HttpStatus statusCode) throws IOException {
        if (this.statusMapping.containsKey(statusCode)) {
            this.extract((Class)this.statusMapping.get(statusCode), response);
        } else if (this.seriesMapping.containsKey(statusCode.series())) {
            this.extract((Class)this.seriesMapping.get(statusCode.series()), response);
        } else {
            super.handleError(response, statusCode);
        }

    }
	//轉(zhuǎn)換抽取為RestClientException異常
    private void extract(@Nullable Class<? extends RestClientException> exceptionClass, ClientHttpResponse response) throws IOException {
        if (exceptionClass != null) {
            HttpMessageConverterExtractor<? extends RestClientException> extractor = new HttpMessageConverterExtractor(exceptionClass, this.messageConverters);
            RestClientException exception = (RestClientException)extractor.extractData(response);
            if (exception != null) {
                throw exception;
            }
        }
    }
}

NoOpResponseErrorHandler

	//在TestRestTemplate類中
    private static class NoOpResponseErrorHandler extends DefaultResponseErrorHandler {
        private NoOpResponseErrorHandler() {
        }
		//不做錯(cuò)誤處理
        public void handleError(ClientHttpResponse response) throws IOException {
        }
    }

RestTemplate異常處理器被觸發(fā)源碼

1. 初始化errorHandler變量
   
2. 執(zhí)行doExecute()方法

    @Nullable
    protected <T> T doExecute(URI url, @Nullable HttpMethod method, @Nullable RequestCallback requestCallback, @Nullable ResponseExtractor<T> responseExtractor) throws RestClientException {
        Assert.notNull(url, "URI is required");
        Assert.notNull(method, "HttpMethod is required");
        ClientHttpResponse response = null;

        Object var14;
        try {
            ClientHttpRequest request = this.createRequest(url, method);
            if (requestCallback != null) {
                requestCallback.doWithRequest(request);
            }

            response = request.execute();
            //處理響應(yīng)
            this.handleResponse(url, method, response);
            var14 = responseExtractor != null ? responseExtractor.extractData(response) : null;
        } catch (IOException var12) {
            String resource = url.toString();
            String query = url.getRawQuery();
            resource = query != null ? resource.substring(0, resource.indexOf(63)) : resource;
            throw new ResourceAccessException("I/O error on " + method.name() + " request for \"" + resource + "\": " + var12.getMessage(), var12);
        } finally {
            if (response != null) {
                response.close();
            }

        }

        return var14;
    }

3. 處理響應(yīng)，調(diào)用handleResponse()方法

    protected void handleResponse(URI url, HttpMethod method, ClientHttpResponse response) throws IOException {
    	//獲取異常處理器
        ResponseErrorHandler errorHandler = this.getErrorHandler();
        boolean hasError = errorHandler.hasError(response);
        if (this.logger.isDebugEnabled()) {
            try {
                int code = response.getRawStatusCode();
                HttpStatus status = HttpStatus.resolve(code);
                this.logger.debug("Response " + (status != null ? status : code));
            } catch (IOException var8) {
            }
        }

        if (hasError) {
            errorHandler.handleError(url, method, response);
        }

    }

4. 獲取異常處理器，調(diào)用getErrorHandler()方法

    public ResponseErrorHandler getErrorHandler() {
    	//返回的就是RestTemplate中的成員變量errorHandler
        return this.errorHandler;
    }

RestTemplate異常處理器實(shí)踐模板

定義一個(gè)自定義的errorHandler實(shí)現(xiàn)ResponseErrorHandler接口

1. errorHandler

/**
 * 繼承默認(rèn)錯(cuò)誤處理器DefaultResponseErrorHandler，無需關(guān)注hasError和handlerError方法
 */
@Component
public class MyResponseErrorHandler implements ResponseErrorHandler {

    private static final Logger LOGGER = LoggerFactory.getLogger(MyResponseErrorHandler.class);

    /**
     * my service進(jìn)行定制化處理
     */
    @Autowired
    private MyService myService;
    
    @Override
    public boolean hasError(ClientHttpResponse clientHttpResponse) throws IOException {
        return clientHttpResponse.getStatusCode().value() != 200 && clientHttpResponse.getStatusCode().value() != 201 && clientHttpResponse.getStatusCode().value() !=302;
    }

    @Override
    public void handleError(ClientHttpResponse clientHttpResponse) throws IOException {
        //遇到401進(jìn)行單獨(dú)處理
        if (HttpStatus.UNAUTHORIZED.value() == response.getStatusCode().value()) {
            myService.doSomething(url.getHost());
        } else {
        	//繼續(xù)拋異常
            throw new RuntimeException(clientHttpResponse.getStatusText());
        }
    }
    @Override
    public void handleError(URI url, HttpMethod method, ClientHttpResponse response) throws IOException {
        LOGGER.error("=======================ERROR HANDLER============================");
        LOGGER.error("DateTime：{}", PoolUtil.currentTime());
        LOGGER.error("HOST:{},URI：{}", url.getHost(), url.getPath());
        LOGGER.error("Method：{}", method.name());
        LOGGER.error("Exception：{}", response.getStatusCode());
        LOGGER.error("StatusText: {}", response.getStatusText());
        LOGGER.error("========================================================");
    }
}

2. HttpClientUtils工具類

@Slf4j
public class HttpClientUtils {
	//http協(xié)議
    private static final String HTTP_PROTOCOL = "http";
  	//https協(xié)議
    private static final String HTTPS_PROTOCAL = "https";
	//最大連接數(shù)
    private static final int MAX_CONNECT = 300;
    //默認(rèn)連接數(shù)
    private static final int DEFAULT_CONNECT = 200;
    public HttpClientUtils(){

    }
	/**
	 * new一個(gè)http client
	 */
    public static CloseableHttpClient newHttpClientForHttpsOrHttp()  {
        HttpClientBuilder build = HttpClientBuilder.create();

        try {
             SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustStrategy() {
                public boolean isTrusted(X509Certificate[] arg0, String arg1){
                    return true;
                }
            }).build();
            build.setSslcontext(sslContext);
            //X509HostnameVerifier校驗(yàn)
            X509HostnameVerifier hostnameVerifier = new X509HostnameVerifier() {
                public boolean verify(String arg0, SSLSession arg1) {
                    return true;
                }
                public void verify(String arg0, SSLSocket arg1){}
                public void verify(String arg0, String[] arg1, String[] arg2){}
                public void verify(String arg0, X509Certificate arg1){}
            };
			//SSL連接socket工廠
            SSLConnectionSocketFactory sslSocketFactory = new SSLConnectionSocketFactory(sslContext, hostnameVerifier);
            //http和https協(xié)議register
            Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory> create()
                    .register(HTTP_PROTOCOL, PlainConnectionSocketFactory.getSocketFactory()).register(HTTPS_PROTOCAL, sslSocketFactory)
                    .build();

	        //連接池
            PoolingHttpClientConnectionManager poolingHttpClientConnectionManager = new PoolingHttpClientConnectionManager(socketFactoryRegistry);
            connMgr.setDefaultMaxPerRoute(DEFAULT_CONNECT_NUM);
            connMgr.setMaxTotal(MAX_CONNECT_NUM);
            build.setConnectionManager(poolingHttpClientConnectionManager);
			//構(gòu)建CloseableHttpClient
            CloseableHttpClient closeableHttpClient = build.build();
            return closeableHttpClient;
        } catch (Exception e ) {
        	log.error("異常:{}", e.getLocalizedMessage());
        }
        return null;
    }

}

4. restTemplate調(diào)用

    /**
     * 獲取遠(yuǎn)程連接template
     *
     * @return
     */
    public static RestTemplate getRestTempte() {
        try {
            HttpComponentsClientHttpRequestFactory factory = new HttpComponentsClientHttpRequestFactory(HttpClientUtils.newHttpClientForHttpsOrHttp());
            factory.setConnectTimeout(30000);
            //設(shè)置handler
            return new RestTemplate(factory).setErrorHandler(new MyResponseErrorHandler());
        } catch (Exception e) {
            return null;
        }
    }

定義一個(gè)自定義的errorHandler繼承DefaultResponseErrorHandler類

/**
 * 繼承默認(rèn)錯(cuò)誤處理器DefaultResponseErrorHandler，無需關(guān)注hasError和handlerError方法
 */
@Component
public class MyResponseErrorHandler extends DefaultResponseErrorHandler {

    private static final Logger LOGGER = LoggerFactory.getLogger(MyResponseErrorHandler.class);

    /**
     * my service進(jìn)行定制化處理
     */
    @Autowired
    private MyService myService;

    @Override
    public void handleError(URI url, HttpMethod method, ClientHttpResponse response) throws IOException {
        LOGGER.error("=======================ERROR HANDLER============================");
        LOGGER.error("DateTime：{}", PoolUtil.currentTime());
        LOGGER.error("HOST:{},URI：{}", url.getHost(), url.getPath());
        LOGGER.error("Method：{}", method.name());
        LOGGER.error("Exception：{}", response.getStatusCode());
        LOGGER.error("StatusText: {}", response.getStatusText());
        LOGGER.error("========================================================");
        //遇到401進(jìn)行單獨(dú)處理
        if (HttpStatus.UNAUTHORIZED.value() == response.getStatusCode().value()) {
            myService.doSomething(url.getHost());
        } else {
            this.handleError(response);
        }
    }
}

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