Java语言程序设计基础篇_编程练习题**17.21 (十六进制编辑器)

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题目：**17.21 (十六进制编辑器)

代码示例

结果展示

题目：**17.21 (十六进制编辑器)

编写一个 GUI 应用程序，让用户在文本域输入一个文件名，然后按回车键，在文本域显示它的十六进制表达形式。用户也可以修改十六进制代码，然后将它回存到这个文件中，如图17-23b所示。

代码示例

编程练习题17_21HexEditor.java

package chapter_17;import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import javafx.scene.input.KeyCode;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;public class 编程练习题17_21HexEditor extends Application{private TextField tfInput;private TextArea textArea;private String FilePath;@Overridepublic void start(Stage primaryStage) throws Exception {VBox vBox = getPane();tfInput.setOnKeyPressed(e ->{if(e.getCode() == KeyCode.ENTER) {try{readFile();}catch (IOException ex) {ex.printStackTrace();}}});Scene scene = new Scene(vBox);primaryStage.setTitle("编程练习题17_21HexEditor");primaryStage.setScene(scene);primaryStage.show();}public VBox getPane() {VBox vBox = new VBox();tfInput = new TextField();tfInput.setPrefWidth(300);Label lbInput = new Label("Enter a file:",tfInput);lbInput.setContentDisplay(ContentDisplay.RIGHT);textArea = new TextArea();Button btSave = new Button("Save the change");btSave.setOnAction(e ->{try {saveFile();}catch (IOException ex) {ex.printStackTrace();}});vBox.setAlignment(Pos.CENTER);vBox.getChildren().addAll(lbInput,tfInput,textArea,btSave);return vBox;}public void readFile() throws IOException{FilePath = tfInput.getText().replaceAll("\\\\", "/");if(!FilePath.isEmpty()) {try(FileInputStream input = new FileInputStream(FilePath);){int read;while((read = input.read()) != -1) {if (read == '\n') { // 仅检查 \n  textArea.appendText("\n");}elsetextArea.appendText(getHex(read)+" ");}}}}public void saveFile() throws IOException {  if (!FilePath.isEmpty()) {  try (BufferedWriter writer = new BufferedWriter(new FileWriter(FilePath))) {  String text = textArea.getText();  String[] s = text.split(" ");for(String str:s) {if(str.contains("\n")) {writer.write('\n');}int i = hexStringToDecimal(str);writer.write((char)i);}}  }  }public static int hexStringToDecimal(String hex) {  return Integer.parseInt(hex,16);}public static String getHex(int value) {return Integer.toHexString(value);}public static void main(String[] args) {Application.launch(args);}
}