Java6的新特性

codecraft
Java语言特性系列

本文梳理了下java6的新特性,相对于java5而言,java6的特性显得少些,分量也不那么重,相当于java5是windows xp,java6有点像vista。

特性列表

  • JSR223脚本引擎
  • JSR199--Java Compiler API
  • JSR269--Pluggable Annotation Processing API
  • 支持JDBC4.0规范
  • JAX-WS 2.0规范

1、JSR223脚本引擎

Scripting for the Java Platform

  • 基本使用

    public class BasicScripting {
      public void greet() throws ScriptException {
          ScriptEngineManager manager = new ScriptEngineManager();
          //支持通过名称、文件扩展名、MIMEtype查找
          ScriptEngine engine = manager.getEngineByName("JavaScript");
    //        engine = manager.getEngineByExtension("js");
    //        engine = manager.getEngineByMimeType("text/javascript");
          if (engine == null) {
              throw new RuntimeException("找不到JavaScript语言执行引擎。");
          }
          engine.eval("println('Hello!');");
      }
      public static void main(String[] args) {
          try {
              new BasicScripting().greet();
          } catch (ScriptException ex) {
              Logger.getLogger(BasicScripting.class.getName()).log(Level.SEVERE, null, ex);
          }
      }
    }
  • 绑定上下文

    public class ScriptContextBindings extends JsScriptRunner {
      public void scriptContextBindings() throws ScriptException {
          ScriptEngine engine = getJavaScriptEngine();
          ScriptContext context = engine.getContext();
          Bindings bindings1 = engine.createBindings();
          bindings1.put("name", "Alex");
          context.setBindings(bindings1, ScriptContext.GLOBAL_SCOPE);
          Bindings bindings2 = engine.createBindings();
          bindings2.put("name", "Bob");
          context.setBindings(bindings2, ScriptContext.ENGINE_SCOPE);
          engine.eval("println(name);");
      }
      public void useScriptContextValues() throws ScriptException {
          ScriptEngine engine = getJavaScriptEngine();
          ScriptContext context = engine.getContext();
          Bindings bindings = context.getBindings(ScriptContext.ENGINE_SCOPE);
          bindings.put("name", "Alex");
          engine.eval("println(name);");
      }
      public void attributeInBindings() throws ScriptException {
          ScriptEngine engine = getJavaScriptEngine();
          ScriptContext context = engine.getContext();
          context.setAttribute("name", "Alex", ScriptContext.GLOBAL_SCOPE);
          engine.eval("println(name);");
      }
      /**
       * @param args the command line arguments
       */
      public static void main(String[] args) throws ScriptException {
          ScriptContextBindings scb = new ScriptContextBindings();
          scb.scriptContextBindings();
          scb.useScriptContextValues();
          scb.attributeInBindings();
      }
    }

    2、JSR199--Java Compiler API

    public class JavaCompilerAPICompiler {
      public void compile(Path src, Path output) throws IOException {
          JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
          try (StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null)) {
              Iterable<? extends JavaFileObject> compilationUnits = fileManager.getJavaFileObjects(src.toFile());
              Iterable<String> options = Arrays.asList("-d", output.toString());
              JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, null, options, null, compilationUnits);
              boolean result = task.call();
          }
      }
    }

    3、JSR269--Pluggable Annotation Processing API

    一部分是进行注解处理的javax.annotation.processing,另一部分是对程序的静态结构进行建模的javax.lang.model

    4、其他

  • 支持JDBC4.0规范
  • JAX-WS 2.0规范(包括JAXB 2.0)
  • 轻量级HttpServer

参考

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