整体的步骤就是

1. 用keystore生成服务器端所用的密钥，用它配置服务器

2.客户端导入其中的公钥，将其添加到信任的证书库中。

下面是具体的参考资料。

1.密码学基础（像我这样非科班出身的需要看一下，知其然还得知其所以然）
http://www.williamlong.info/archives/499.html

2.keytool使用与tomcat配置
英文好的朋友请直接看tomcat文档，SSL部分；
英文不好的朋友请寻找中文版文档，或者看这篇文章：
http://ln-ydc.iteye.com/blog/1330674

注意：具体的配置可能不一样，请找你的tomcat文档，SSL部分。

<!-- 不配置APR时 -->
    <Connector port="8443" protocol="org.apache.coyote.http11.Http11Protocol"
               maxThreads="150" SSLEnabled="true" scheme="https" secure="true"
               clientAuth="false" sslProtocol="TLS" 
			   keystoreFile="conf/cert/tomcat.keystore" keystorePass="password"
			   />

3.android配置
如果不需要验证服务器端证书，直接照这里做
http://elsila.blog.163.com/blog/static/17319715820101128832427/

如果需要验证服务器端证书（这样能够防钓鱼），我是这样做的，还有些问题问大牛：
a. 导出公钥。在浏览器上用https访问tomcat，查看其证书，并另存为一个文件(存成了X.509格式：xxxx.cer)

b. 导入公钥。把xxxx.cer放在Android的assets文件夹中，以方便在运行时通过代码读取此证书。

获取本地的证书
public static KeyStore getCertificate(Context context) {
		AssetManager assetManager = context.getAssets();
		InputStream ins = null;
		KeyStore keyStore = null;
		try {
			ins = assetManager.open("darrenf.crt");
			// 读取证书
			CertificateFactory cerFactory = CertificateFactory.getInstance("X.509"); //Certificate的type
			Certificate cer = cerFactory.generateCertificate(ins);
			// 创建一个证书库，并将证书导入证书库
			//android平台上支持的keystore type好像只有PKCS12，不支持JKS
			keyStore = KeyStore.getInstance("PKCS12", "BC"); 
			keyStore.load(null, null);

			keyStore.setCertificateEntry("trust", cer);
			return keyStore;

		} catch (IOException e) {
			e.printStackTrace();
		} catch (CertificateException e) {
			e.printStackTrace();
		} catch (KeyStoreException e) {
			e.printStackTrace();
		} catch (NoSuchProviderException e) {
			e.printStackTrace();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} finally {
			try {
				if(ins != null){
					ins.close();
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return keyStore;
	}

// 连接服务器获取信息
	public void connectServer() {
		// 获取本地证书
		KeyStore keystore = CertificateUtils.getCertificate(getContext());
		if(keystore == null){
			Log.e(TAG, "获取证书错误");
			return;
		}
		// 把咱的证书库作为信任证书库
		SSLSocketFactory socketFactory = null;
		try {
			socketFactory = new SSLSocketFactory(keystore);
			// 允许所有主机
			socketFactory.setHostnameVerifier(SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
		} catch (KeyManagementException e) {
			e.printStackTrace();
		} catch (UnrecoverableKeyException e) {
			e.printStackTrace();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (KeyStoreException e) {
			e.printStackTrace();
		}
		final Scheme sch = new Scheme("https", socketFactory, 443);

		Thread thread = new Thread() {

			public void run() {
				String path = "https://192.168.16.34:8443/SpringREST/simple/22";
				HttpClient mHttpClient = new DefaultHttpClient();
				mHttpClient.getConnectionManager().getSchemeRegistry().register(sch);

				HttpGet httpGet = new HttpGet(path);
				InputStream inputStream = null;
				ByteArrayOutputStream baos = null;
				try {
					HttpResponse response = mHttpClient.execute(httpGet);
					StatusLine stateLine = response.getStatusLine();
					if (stateLine.getStatusCode() == HttpStatus.SC_OK) {
						HttpEntity entity = response.getEntity();
						inputStream = entity.getContent();

						baos = new ByteArrayOutputStream();
						int len = 0;
						byte[] buffer = new byte[1024];
						while ((len = inputStream.read(buffer)) != -1) {
							baos.write(buffer, 0, len);
						}
						String content = new String(baos.toByteArray());
					}
				} catch (ClientProtocolException e) {
					e.printStackTrace();
				} catch (IOException e) {
					e.printStackTrace();
				} finally {
					try {
						if (baos != null) {
							baos.close();
						}
						if (inputStream != null) {
							inputStream.close();
						}
					} catch (IOException e) {
						e.printStackTrace();
					}
				}
			}
		};
		thread.start();
	}

web.xml中配置http访问转向https

<!-- 配置使http访问转向https -->
	<security-constraint>
		<web-resource-collection>
			<web-resource-name>SSL</web-resource-name>
			<url-pattern>/*</url-pattern>
		</web-resource-collection>
		<user-data-constraint>
			<transport-guarantee>CONFIDENTIAL</transport-guarantee>
		</user-data-constraint>
	</security-constraint>

为 Tomcat 安装 apr

http://pengranxiang.iteye.com/blog/1128905