(09) Apache Felix 入门 - 09

1、Spell Checker Client Bundle

此例子和 Example6 很类似，不一样的是我们在这里使用了 SpellChecker 服务检测用户输入句子中的错误单词，并且使用 ServiceTracker 获取 SpellChecker 服务，具体代码如下:

/*
 * Apache Felix OSGi tutorial.
**/

package tutorial.example7;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.util.tracker.ServiceTracker;

import tutorial.example6.service.SpellChecker;

/**
 * 使用了 ServiceTracker 动态监测 SpellChecker 服务是否可用，
 * 并使用 SpellChecker 检测用户输入的句子中的错误单词。
**/
public class Activator implements BundleActivator
{
    // Bundle's context.
    private BundleContext m_context = null;
    // The service tacker object.
    private ServiceTracker m_tracker = null;

    /**
     * Implements BundleActivator.start(). Creates a Service
     * Tracker object to monitor spell checker services. Enters
     * a spell check loop where it reads passages from standard
     * input and checks their spelling using the spell checker service.
     * (NOTE: It is very bad practice to use the calling thread
     * to perform a lengthy process like this; this is only done
     * for the purpose of the tutorial.)
     * @param context the framework context for the bundle.
    **/
    public void start(BundleContext context) throws Exception
    {
        m_context = context;

        // Create a service tracker to monitor dictionary services.
        m_tracker = new ServiceTracker(
            m_context,
            m_context.createFilter(
                "(objectClass=" + SpellChecker.class.getName() + ")"),
            null);
        m_tracker.open();

        try
        {
            System.out.println("Enter a blank line to exit.");
            String passage = "";
            BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

            // Loop endlessly.
            while (true)
            {
                // Ask the user to enter a passage.
                System.out.print("Enter passage: ");
                passage = in.readLine();

                // Get the selected dictionary service, if available.
                SpellChecker checker = (SpellChecker) m_tracker.getService();

                // If the user entered a blank line, then
                // exit the loop.
                if (passage.length() == 0)
                {
                    break;
                }
                // If there is no spell checker, then say so.
                else if (checker == null)
                {
                    System.out.println("No spell checker available.");
                }
                // Otherwise check passage and print misspelled words.
                else
                {
                    String[] errors = checker.check(passage);

                    if (errors == null)
                    {
                        System.out.println("Passage is correct.");
                    }
                    else
                    {
                        System.out.println("Incorrect word(s):");
                        for (int i = 0; i < errors.length; i++)
                        {
                            System.out.println("    " + errors[i]);
                        }
                    }
                }
            }
        } catch (Exception ex) { }
    }

    /**
     * Implements BundleActivator.stop(). Does nothing since
     * the framework will automatically unget any used services.
     * @param context the framework context for the bundle.
    **/
    public void stop(BundleContext context)
    {
    }
}

构建 manifest.mf:

Bundle-Name: Spell checker client
Bundle-Description: A bundle that uses the spell checker service
Bundle-Vendor: Richard Hall
Bundle-Version: 1.0.0
Bundle-Activator: tutorial.example7.Activator
Import-Package: org.osgi.framework,
 org.osgi.util.tracker,
 tutorial.example6.service

编译、打包：

D:\devInstall\apache\felix-framework-6.0.0\examples\demo07\src> javac -cp ../../example6/target/example6.jar;../../../bin/felix.jar -encoding UTF-8 -d ../target ./tutorial/example7/Activator.java
D:\devInstall\apache\felix-framework-6.0.0\examples\demo07\src> cd ../target
D:\devInstall\apache\felix-framework-6.0.0\examples\demo07\src> cp ../src/manifest.mf ./
D:\devInstall\apache\felix-framework-6.0.0\examples\demo07\src> jar cvfm example7.jar ./manifest.mf -C . .
已添加清单
正在添加: manifest.mf(输入 = 291) (输出 = 181)(压缩了 37%)
正在添加: tutorial/(输入 = 0) (输出 = 0)(存储了 0%)
正在添加: tutorial/example7/(输入 = 0) (输出 = 0)(存储了 0%)
正在添加: tutorial/example7/Activator.class(输入 = 2218) (输出 = 1233)(压缩了 44%)

安装、运行:

g! install file:./examples/demo07/target/example7.jar
Bundle ID: 23
g! start 23
Enter a blank line to exit.
Enter passage: ~
g! lb
START LEVEL 1
   ID|State      |Level|Name
    0|Active     |    0|System Bundle (6.0.0)|6.0.0
    1|Active     |    1|jansi (1.17.1)|1.17.1
    2|Active     |    1|JLine Bundle (3.7.0)|3.7.0
    3|Active     |    1|Apache Felix Bundle Repository (2.0.10)|2.0.10
    4|Active     |    1|Apache Felix Gogo Command (1.0.2)|1.0.2
    5|Active     |    1|Apache Felix Gogo JLine Shell (1.1.0)|1.1.0
    6|Active     |    1|Apache Felix Gogo Runtime (1.1.0)|1.1.0
    7|Active     |    1|Service listener example (1.0.0)|1.0.0
   20|Active     |    1|Spell checker service (1.0.0)|1.0.0
   21|Active     |    1|English dictionary (1.0.0)|1.0.0
   23|Active     |    1|Spell checker client (1.0.0)|1.0.0

当名称为 Spell checker client 的 bundle 启动的时候，如果系统中存在 spell checker 服务，则使用该服务循环检测用户每次输入的句子中的错误单词。