【 Android 】CSV 文件在 Android 开发中的应

Android 从服务器读取数据通常情况下都是读取的 Json 数据，其实 .csv 文件也有同样的效果。本文将围绕两方面进行讲解：① 读取 .csv 文件 ② 将数据写入到 .csv 文件里。

一、读取 .csv 文件

① .csv文件是可以用 Excel 或者记事本打开和编辑的。先看一个示例文件

.csv 文件

② 读取.csv文件，并显示在 UI 上
通过示例图，我们需要创建一个bean拿到id、name、age的getter和setter方法。

public class TestDataBean {

    private int id;

    private String name;

    private int age;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public TestDataBean(int id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }
}

③ 公开一个读取.csv文件的方法

private ArrayList<TestDataBean> readCsv(String path) {
    ArrayList<TestDataBean> readerArr = new ArrayList<>();
    File file = new File(path);
    FileInputStream fileInputStream;
    Scanner in;
    try {
        fileInputStream = new FileInputStream(file);
        in = new Scanner(fileInputStream, "UTF-8");
        in.nextLine();
        while (in.hasNextLine()) {
            String[] lines = in.nextLine().split(",");
            TestDataBean bean = new TestDataBean(Integer.parseInt(lines[0]), lines[1], Integer.parseInt(lines[2]));
            readerArr.add(bean);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

    return readerArr;
}

④ 通过adb命令将.csv文件写入到包名下的file文件夹里面
6.0 之前的系统：

adb push "文件路径\xxx.csv" /data/data/包名/files/

6.0 之后的系统：

adb push "文件路径\xxx.csv" /data/user/0/包名/files/

⑤ 读取.csv文件并显示在 UI 上
效果图：

读文件

示例代码：

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private static final String TAG = MainActivity.class.getSimpleName();

    private RecyclerView mRecyclerView;

    private List<TestDataBean> mList;

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

        initView();
    }

    private void initView() {
        Button mBtnRead = findViewById(R.id.btn_read);
        mRecyclerView = findViewById(R.id.rcv_main);

        mBtnRead.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_read:
                readCsvFile();
                break;
            default:
                break;
        }
    }

    private void readCsvFile() {
        mList = readCsv(this.getFilesDir().getAbsolutePath() + File.separator + "csv_file" + ".csv");

        if (mList.size() > 0) {
            Snackbar.make(mRecyclerView, "Csv 文件读取成功", Snackbar.LENGTH_SHORT).show();
        } else {
            Snackbar.make(mRecyclerView, "Csv 文件读取失败", Snackbar.LENGTH_SHORT).show();
        }

        MainAdapter mAdapter = new MainAdapter(this);

        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mRecyclerView.setHasFixedSize(true);
        mRecyclerView.setAdapter(mAdapter);

        mAdapter.setDataList(mList);
    }

    private ArrayList<TestDataBean> readCsv(String path) {
        ArrayList<TestDataBean> readerArr = new ArrayList<>();
        File file = new File(path);
        FileInputStream fileInputStream;
        Scanner in;
        try {
            fileInputStream = new FileInputStream(file);
            in = new Scanner(fileInputStream, "UTF-8");
            in.nextLine();
            while (in.hasNextLine()) {
                String[] lines = in.nextLine().split(",");
                TestDataBean bean = new TestDataBean(Integer.parseInt(lines[0]), lines[1], Integer.parseInt(lines[2]));
                readerArr.add(bean);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return readerArr;
    }
}

public class MainAdapter extends RecyclerView.Adapter<MainAdapter.MainViewHolder> {

    private static final String TAG = MainAdapter.class.getSimpleName();

    private Context mContext;

    private List<TestDataBean> mList = new ArrayList<>();

    public MainAdapter(Context context) {
        mContext = context;
    }

    public void setDataList(List<TestDataBean> list) {
        mList = list;

        Log.d(TAG, "setDataList: " + mList.size());

        notifyDataSetChanged();
    }

    @Override
    public MainViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(mContext).inflate(R.layout.item_main, parent, false);
        return new MainViewHolder(view);
    }

    @Override
    public void onBindViewHolder(MainViewHolder holder, int position) {
        holder.tvId.setText(mList.get(position).getId() + "");
        holder.tvName.setText(mList.get(position).getName() + "");
        holder.tvAge.setText(mList.get(position).getAge() + "");
    }

    @Override
    public int getItemCount() {
        return mList == null ? 0 : mList.size();
    }

    public class MainViewHolder extends RecyclerView.ViewHolder {

        TextView tvId, tvName, tvAge;

        public MainViewHolder(View itemView) {
            super(itemView);
            tvId = itemView.findViewById(R.id.tv_id);
            tvName = itemView.findViewById(R.id.tv_name);
            tvAge = itemView.findViewById(R.id.tv_age);
        }
    }
}

代码清晰明了，没有一句多余代码，就不做过多解释了。

二、写入 .csv 文件

① 公开一个写入.csv文件的方法，将数据写入到.csv文件里

private void writeCsvFile() {
    try {
        File file = new File(this.getFilesDir().getAbsolutePath() + File.separator + "new_csv_file" + ".csv");
        BufferedWriter bw = new BufferedWriter(new FileWriter(file, true));
        // 添加头部名称
        bw.write("id" + "," + "name" + "," + "age");
        bw.newLine();
        for (int i = 0; i < mList.size(); i++) {
            bw.write(mList.get(i).getId() + "," + mList.get(i).getName() + "," + mList.get(i).getAge());
            bw.newLine();
        }
        bw.close();

        Snackbar.make(mRecyclerView, "Csv 文件已生成", Snackbar.LENGTH_SHORT).show();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

其中mList就是上面读取的数据，代码清晰明了，不做过多解释。

② 验证新的.csv文件是否写入成功

写入文件
从图中我们可以看到新文件已经生成，我们通过adb pull将文件拉取出来，看看是否真的写入了。

拉取文件之后打开文件查看内容：

新的 .csv 文件

证明写入成功！

三、使用 Apache Commons CSV 读写 .csv 文件

① 导入必要的库

implementation 'org.apache.commons:commons-csv:1.5'

② 代码部分

// 初始化 List
private List<ApacheBean> mList = new ArrayList<>();

// .csv 文件路径
String path = getFilesDir().getAbsolutePath() + File.separator + "test_file" + ".csv";

// 读取 .csv 文件
private void readCsv(String path) {
    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(path), "UTF-8"));  // 防止出现乱码
        CSVParser csvParser = new CSVParser(reader, CSVFormat.DEFAULT.withFirstRecordAsHeader().withIgnoreHeaderCase().withTrim());
        Iterable<CSVRecord> csvRecords = csvParser.getRecords();
        for (CSVRecord csvRecord : csvRecords) {
            ApacheBean apacheBean = new ApacheBean();
            apacheBean.setId(Integer.parseInt(csvRecord.get("id")));
            apacheBean.setName(csvRecord.get("name"));
            apacheBean.setAge(Integer.parseInt(csvRecord.get("age")));
            mList.add(apacheBean);
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

// 写入 .csv 文件
private void writeCsv() {
    try {
        File file = new File(this.getFilesDir().getAbsolutePath() + File.separator + "new_test_file" + ".csv");
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), "UTF-8"));  // 防止出现乱码
        // 添加头部
        CSVPrinter csvPrinter = new CSVPrinter(writer, CSVFormat.DEFAULT.withHeader("id", "name", "age"));
        // 添加内容
        for (int i = 0; i < mList.size(); i++) {
            csvPrinter.printRecord(
                    mList.get(i).getId(),
                    mList.get(i).getName(),
                    mList.get(i).getAge(),
                    mList.get(i).getCompany(),
                    mList.get(i).getAddress());
        }
        csvPrinter.printRecord();
        csvPrinter.flush();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

以上就是.csv文件在Android中的应用。