在android中将csv格式转换为Json

Question

在 android 中将 csv 格式转换为 Json 的示例。我在Converting an CSV file to a JSON object in Java 中找到了解决方案，但没有工作，或者我遗漏了任何东西。

提前致谢。

  package com.example.readfilefromsdcard;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.Reader;
 import java.util.List;

 import org.codehaus.jackson.map.ObjectMapper;

 import com.opencsv.bean.ColumnPositionMappingStrategy;
 import com.opencsv.bean.CsvToBean;
 import com.opencsv.bean.HeaderColumnNameMappingStrategy;
 import android.app.Activity;
 import android.os.Bundle;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
 import android.widget.Toast;

  public class MainActivity extends Activity {

Button btnWriteSDFile;
Button btnReadSDFile;
String path = "/sdcard/mydocs/test.csv";


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btnReadSDFile = (Button) findViewById(R.id.btnReadSDFile);
    btnReadSDFile.setOnClickListener(new OnClickListener() {

        public void onClick(View v) {
            try {
                 ConvertCsvToJson(path,"TestJavaBeans");
                // ConvertCsvToJson1(path);
            } catch (Exception e) {
                Toast.makeText(getBaseContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
            }
        }
    });
}

public void ConvertCsvToJson(String path, String clsName) throws IOException, ClassNotFoundException {

    String pathToCsvFile = path;
    String javaBeanClassName = "" + clsName;
    final File file = new File(pathToCsvFile);
    if (!file.exists()) {
        System.out.println("The file you specified does not exist. path=" + pathToCsvFile);
    }
    Class<?> type = null;
    try {
        type = Class.forName(javaBeanClassName);
    } catch (ClassNotFoundException e) {
        System.out.println("The java bean you specified does not exist. className=" + javaBeanClassName);
    }

    HeaderColumnNameMappingStrategy<TestJavaBeans> strat = new HeaderColumnNameMappingStrategy<TestJavaBeans>();
    //strat.setType(type);
    CsvToBean<TestJavaBeans> csv = new CsvToBean<TestJavaBeans>();
    List<TestJavaBeans> list = csv.parse(strat, new InputStreamReader(new FileInputStream(file)));
    System.out.println(new ObjectMapper().writeValueAsString(list));

}

public void ConvertCsvToJson1(String path) throws IOException, ClassNotFoundException {

    final ColumnPositionMappingStrategy<TestJavaBeans > strategy = new ColumnPositionMappingStrategy<TestJavaBeans>();
    strategy.setType(TestJavaBeans .class);
    strategy.setColumnMapping(new String[] { "name", "id", });
    final CsvToBean<TestJavaBeans > csvToBean = new CsvToBean<TestJavaBeans >();
    final List<TestJavaBeans > beanExamples;
    try {
        final Reader reader = new FileReader(path);
        beanExamples = csvToBean.parse(strategy, reader);
        System.out.println(new       ObjectMapper().writeValueAsString(beanExamples));
    } catch (IOException ex) {
        throw new RuntimeException(ex);
    }
}

}

  package com.example.readfilefromsdcard;

 public class TestJavaBeans {
       private String name;
       private String id;
       public String getName() {
         return name;
}
public void setName(String name) {
    this.name = name;
}
public String getId() {
    return id;
}
public void setId(String id) {
    this.id = id;
}

}

参考库：jackson-all-1.9.0.jar 和 opencsv-3.3.jar

日志：找不到方法 java.beans.Introspector.getBeanInfo，引用自方法 com.opencsv.bean.HeaderColumnNameMappingStrategy.loadDescriptors

Answer 1

确实没有通用的“转换”：JSON 是层次结构，而 CSV 是扁平结构。您需要对 JSON 对象进行建模，并将 CSV 中的字段一次映射到 JSON 对象。这更像是一个逻辑问题，而不是编码问题。

Answer 2

我会建议这种方法

创建一个具有类变量List<TestJavaBeans> list的Java“包装器”类

然后使用Jackson将这个“包装器”转换为json

Answer 3

我更喜欢将 csv 转换为 json 的链接如下：

https://github.com/cparker15/csv-to-json?files=1