详解如何通过tomcat的ManagerServlet远程部署项目

介绍

之前在邮政实习时，leader让我阅读tomcat的源代码，尝试自己实现远程部署项目的功能，于是便有了这此实践。
在Tomact中有一个Manager应用程序，它是用来管理已经部署的web应用程序，在这个应用程序中，ManagerServlet是他的主servlet，通过它我们可以获取tomcat的部分指标，远程管理web应用程序，不过这个功能会受到web应用程序部署中安全约束的保护。

当你请求ManagerServlet时，它会检查getPathInfo()返回的值以及相关的查询参数，以确定被请求的操作。它支持以下操作和参数(从servlet路径开始): 

我们可以通过ManagerServlet中getPathInfo()提供的操作，将自己的项目远程部署到服务器上，下面将贴出我的实践代码，在实践它之前你只需要引入httpclient包和commons包。

封装统一的远程请求管理类

封装此类用于方便client请求ManagerServlet：

import java.io.File;import java.net.URL;import java.net.URLEncoder;import org.apache.commons.io.IOUtils;import org.apache.commons.lang.StringUtils;import org.apache.http.Header;import org.apache.http.HttpHost;import org.apache.http.HttpResponse;import org.apache.http.HttpStatus;import org.apache.http.auth.AuthScope;import org.apache.http.auth.Credentials;import org.apache.http.auth.UsernamePasswordCredentials;import org.apache.http.client.AuthCache;import org.apache.http.client.methods.HttpGet;import org.apache.http.client.methods.HttpRequestBase;import org.apache.http.client.protocol.ClientContext;import org.apache.http.impl.auth.BasicScheme;import org.apache.http.impl.client.BasicAuthCache;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.impl.conn.PoolingClientConnectionManager;import org.apache.http.protocol.BasicHttpContext;public class TomcatManager {  private static final String MANAGER_CHARSET = "UTF-8";  private String username;  private URL url;  private String password;  private String charset;  private boolean verbose;  private DefaultHttpClient httpClient;  private BasicHttpContext localContext;  /** constructor */  public TomcatManager(URL url, String username) {    this(url, username, "");  }  public TomcatManager(URL url, String username, String password) {    this(url, username, password, "ISO-8859-1");  }  public TomcatManager(URL url, String username, String password, String charset) {    this(url, username, password, charset, true);  }  public TomcatManager(URL url, String username, String password, String charset, boolean verbose) {    this.url = url;    this.username = username;    this.password = password;    this.charset = charset;    this.verbose = verbose;        // 创建网络请求相关的配置    PoolingClientConnectionManager poolingClientConnectionManager = new PoolingClientConnectionManager();    poolingClientConnectionManager.setMaxTotal(5);    this.httpClient = new DefaultHttpClient(poolingClientConnectionManager);    if (StringUtils.isNotEmpty(username)) {      Credentials creds = new UsernamePasswordCredentials(username, password);      String host = url.getHost();      int port = url.getPort() > -1 ? url.getPort() : AuthScope.ANY_PORT;      httpClient.getCredentialsProvider().setCredentials(new AuthScope(host, port), creds);      AuthCache authCache = new BasicAuthCache();      BasicScheme basicAuth = new BasicScheme();      HttpHost targetHost = new HttpHost(url.getHost(), url.getPort(), url.getProtocol());      authCache.put(targetHost, basicAuth);      localContext = new BasicHttpContext();      localContext.setAttribute(ClientContext.AUTH_CACHE, authCache);    }  }  /** 根据指定的path部署并启动一个新的应用程序 */  public TomcatManagerResponse deploy(String path, File war, boolean update) throws Exception {    StringBuilder buffer = new StringBuilder("/deploy");    buffer.append("?path=").append(URLEncoder.encode(path, charset));    if (war != null) {      buffer.append("&war=").append(URLEncoder.encode(war.toString(), charset));    }    if (update) {      buffer.append("&update=true");    }    return invoke(buffer.toString());  }  /** 获取所有已部署的web应用程序的上下文路径。格式为path:status:sessions(活动会话数) */  public TomcatManagerResponse list() throws Exception {    StringBuilder buffer = new StringBuilder("/list");    return invoke(buffer.toString());  }  /** 获取系统信息和JVM信息 */  public TomcatManagerResponse serverinfo() throws Exception {    StringBuilder buffer = new StringBuilder("/serverinfo");    return invoke(buffer.toString());  }  /** 真正发送请求的方法 */  private TomcatManagerResponse invoke(String path) throws Exception {    HttpRequestBase httpRequestBase = new HttpGet(url + path);    HttpResponse response = httpClient.execute(httpRequestBase, localContext);    int statusCode = response.getStatusLine().getStatusCode();    switch (statusCode) {      case HttpStatus.SC_OK: // 200      case HttpStatus.SC_CREATED: // 201      case HttpStatus.SC_ACCEPTED: // 202        break;      case HttpStatus.SC_MOVED_PERMANENTLY: // 301      case HttpStatus.SC_MOVED_TEMPORARILY: // 302      case HttpStatus.SC_SEE_OTHER: // 303      String redirectUrl = getRedirectUrl(response);      this.url = new URL(redirectUrl);      return invoke(path);    }    return new TomcatManagerResponse().setStatusCode(response.getStatusLine().getStatusCode())        .setReasonPhrase(response.getStatusLine().getReasonPhrase())        .setHttpResponseBody(IOUtils.toString(response.getEntity().getContent()));  }    /** 提取重定向URL */  protected String getRedirectUrl(HttpResponse response) {    Header locationHeader = response.getFirstHeader("Location");    String locationField = locationHeader.getValue();    // is it a relative Location or a full ?    return locationField.startsWith("http") ? locationField : url.toString() + '/' + locationField;  }}