Java中更好的代码生成器方法？

问题描述 投票：9回答：5

我有一个带有图形的类。我对图进行迭代并创建一个构建图的字符串，然后将其写入Java文件中。有没有更好的方法可以做到这一点，我阅读了有关JDT和CodeModel的信息，但是我确实需要一些如何使用它的提示。

编辑

我正在做一个正则表达式代码生成器，到目前为止，我已经将正则表达式转换为有向图表示的DFA（使用grail库）。当我拥有DFA时，下一步就是生成具有三个方法的类，第一个方法构建相同的图（DFA），第二个方法从一个节点移动到另一个节点，第三个方法在输入字符串被接受的情况下匹配。只有第一个方法会根据正则表达式输入进行更改，其他两个方法是静态的，并且对于每个生成的java类都是相同的。

我的基于字符串的方法看起来像：

 import grail.interfaces.DirectedEdgeInterface;
 import grail.interfaces.DirectedGraphInterface;
 import grail.interfaces.DirectedNodeInterface;
 import grail.interfaces.EdgeInterface;
 import grail.iterators.EdgeIterator;
 import grail.iterators.NodeIterator;
 import grail.properties.GraphProperties;
 import grail.setbased.SetBasedDirectedGraph;

 public class ClassName {

private SetBasedDirectedGraph graph = new SetBasedDirectedGraph();
private static DirectedNodeInterface state;
private static DirectedNodeInterface currentState;
protected DirectedEdgeInterface edge;

public ClassName() {
    buildGraph();
}

protected void buildGraph() {

    // Creating Graph Nodes (Automaton States)

    state = graph.createNode(3);
    state.setProperty(GraphProperties.LABEL, "3");
    state.setProperty(GraphProperties.DESCRIPTION, "null");
    graph.addNode(state);
    state = graph.createNode(2);
    state.setProperty(GraphProperties.LABEL, "2");
    state.setProperty(GraphProperties.DESCRIPTION, "null");
    graph.addNode(state);
    state = graph.createNode(1);
    state.setProperty(GraphProperties.LABEL, "1");
    state.setProperty(GraphProperties.DESCRIPTION, "Accepted");
    graph.addNode(state);
    state = graph.createNode(0);
    state.setProperty(GraphProperties.LABEL, "0");
    state.setProperty(GraphProperties.DESCRIPTION, "Initial");
    graph.addNode(state);
            .....


    // Creating Graph Edges (Automaton Transitions)

    edge = graph.createEdge(null, (DirectedNodeInterface) graph.getNode(2),
            (DirectedNodeInterface) graph.getNode(1));
    edge.setProperty((GraphProperties.LABEL), "0");
    graph.addEdge(edge);
    edge = graph.createEdge(null, (DirectedNodeInterface) graph.getNode(2),
            (DirectedNodeInterface) graph.getNode(2));
    edge.setProperty((GraphProperties.LABEL), "1");
    graph.addEdge(edge);
    edge = graph.createEdge(null, (DirectedNodeInterface) graph.getNode(1),
            (DirectedNodeInterface) graph.getNode(1));
    edge.setProperty((GraphProperties.LABEL), "0");
    graph.addEdge(edge);
    edge = graph.createEdge(null, (DirectedNodeInterface) graph.getNode(1),
            (DirectedNodeInterface) graph.getNode(3));
    edge.setProperty((GraphProperties.LABEL), "1");
    graph.addEdge(edge);
    edge = graph.createEdge(null, (DirectedNodeInterface) graph.getNode(0),
            (DirectedNodeInterface) graph.getNode(1));
    edge.setProperty((GraphProperties.LABEL), "0");
    graph.addEdge(edge);
    edge = graph.createEdge(null, (DirectedNodeInterface) graph.getNode(0),
            (DirectedNodeInterface) graph.getNode(2));
    edge.setProperty((GraphProperties.LABEL), "1");
    graph.addEdge(edge);
}
}
java code-generation eclipse-jdt sun-codemodel
5个回答
4
投票

另一种解决方案是继续使用当前技术，但在builder pattern中提供一小层。要实施构建器，您只需花费一小笔时间，但可以获得更好的可读性代码。

我实现了代码的第一部分。使用适当的构建器，您可以编写：

graph = new GraphBuilder()
    .createNode(3).setLabel("3").setDescription("null").add()
    .createNode(2).setLabel("2").setDescription("null").add()
    .createNode(1).setLabel("1").setDescription("Accepted").add()
    .createNode(0).setLabel("0").setDescription("Initial").add()
    // unimplemented start
    .createEdge(2, 1).setLabel("0").add()
    .createEdge(2, 2).setLabel("1").add()
    .createEdge(1, 1).setLabel("0").add()
    .createEdge(1, 3).setLabel("1").add()
    .createEdge(0, 1).setLabel("0").add()
    .createEdge(0, 2).setLabel("1").add()
    // unimplemented end
    .build();

更具可读性，不是吗？为此，您需要两个构建器。首先是GraphBuilder：

package at.corba.test.builder;

import java.util.LinkedHashMap;
import java.util.Map;

/**
 * Builder for generating graphs.
 * @author ChrLipp
 */
public class GraphBuilder {
    /** List of StateBuilder, accesable via nodeNumber. */
    Map<Integer, StateBuilder> stateBuilderMap = new LinkedHashMap<Integer, StateBuilder>();

    /**
     * Delegates node-specific building to NodeBuilder.
     * @param nodeNumber Number of node to create
     * @return NodeBuilder for the node instance to create.
     */
    public StateBuilder createNode(final int nodeNumber) {
        StateBuilder builder = new StateBuilder(this);
        stateBuilderMap.put(nodeNumber, builder);
        return  builder;
    }

    /**
     * Builder function to initialise the graph.
     */
    public SetBasedDirectedGraph build() {
        SetBasedDirectedGraph graph = new SetBasedDirectedGraph();

        for (int key : stateBuilderMap.keySet()) {
            StateBuilder builder = stateBuilderMap.get(key);
            State state = graph.createNode(key);
            state = builder.build(state);
            graph.addNode(state);
        }

        return graph;
    }
}

并且比StateBuilder：

package at.corba.test.builder;

import java.util.HashMap;
import java.util.Map;

/**
 * Builder for generating states.
 * @author ChrLipp
 */
public class StateBuilder {
    /** Parent builder */
    private final GraphBuilder graphBuilder;

    /** Properties for this node */
    Map<GraphProperties, String> propertyMap = new HashMap<GraphProperties, String>();

    /**
     * ctor.
     * @param graphBuilder  Link to parent builder
     * @param nodeNumber    Node to create
     */
    public StateBuilder(final GraphBuilder graphBuilder)  {
        this.graphBuilder = graphBuilder;
    }

    /**
     * Property setter for property Label.
     * @param label value for property label
     * @return current NodeBuilder instance for method chaining
     */
    public StateBuilder setLabel(final String label) {
        propertyMap.put(GraphProperties.LABEL, label);
        return this;
    }

    /**
     * Property setter for description Label.
     * @param description value for description label
     * @return current NodeBuilder instance for method chaining
     */
    public StateBuilder setDescription(final String description) {
        propertyMap.put(GraphProperties.DESCRIPTION, description);
        return this;
    }

    /**
     * DSL function to close the node section and to return control to the parent builder.
     * @return
     */
    public GraphBuilder add() {
        return graphBuilder;
    }

    /**
     * Builder function to initialise the node.
     * @return newly generated node
     */
    public State build(final State state) {
        for (GraphProperties key : propertyMap.keySet()) {
            String value = propertyMap.get(key);
            state.setProperty(key, value);
        }

        return state;
    }
}

您将对边缘执行相同的操作，但是我没有实现此:-)。在Groovy中，创建构建器更加容易（我的实现是用Java编写的构建器），例如，请参见Make a builder。

2
投票

以下博客提供了一个非常简单的示例：

2
投票

Java中更好的代码生成器...... ANTLR之类的工具，这是一种现代工具，专门为实现带有代码生成支持的词法分析器/解析器而创建。它具有出色的文档，包括两本书：

1
投票

对这个问题还是有点模糊，但是这里有一些建议：

1
投票

我在几个需要代码生成的项目（例如消息的编码/解码类）中使用了鲜为人知的产品FreeMarker。这是基于Java的解决方案，您可以在其中生成内存模型并将其提供给模板。从他们的主页：

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