介紹

之前在郵政實習時，leader讓我閱讀tomcat的源代碼，嘗試自己實現遠程部署項目的功能，于是便有了這此實踐。
在Tomact中有一個Manager應用程序，它是用來管理已經部署的web應用程序，在這個應用程序中，ManagerServlet是他的主servlet，通過它我們可以獲取tomcat的部分指標，遠程管理web應用程序，不過這個功能會受到web應用程序部署中安全約束的保護。

當你請求ManagerServlet時，它會檢查getPathInfo()返回的值以及相關的查詢參數，以確定被請求的操作。它支持以下操作和參數(從servlet路徑開始): 

我們可以通過ManagerServlet中getPathInfo()提供的操作，將自己的項目遠程部署到服務器上，下面將貼出我的實踐代碼，在實踐它之前你只需要引入httpclient包和commons包。

封裝統一的遠程請求管理類

封裝此類用于方便client請求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;        // 創建網絡請求相關的配置    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);    }  }  /** 根據指定的path部署并啟動一個新的應用程序 */  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());  }  /** 獲取所有已部署的web應用程序的上下文路徑。格式為path:status:sessions(活動會話數) */  public TomcatManagerResponse list() throws Exception {    StringBuilder buffer = new StringBuilder("/list");    return invoke(buffer.toString());  }  /** 獲取系統信息和JVM信息 */  public TomcatManagerResponse serverinfo() throws Exception {    StringBuilder buffer = new StringBuilder("/serverinfo");    return invoke(buffer.toString());  }  /** 真正發送請求的方法 */  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;  }}