Android 柱状图（自定义View）

效果图：

activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ccv.turbosnail.one.PColumn
        android:layout_width="400dp"
        android:layout_height="400dp"
        android:layout_centerInParent="true"/>
    
</RelativeLayout>

新建 PColumn 类并继承 View

PColumn.java：

public class PColumn extends View {
    private static Context context = null;
    private static AttributeSet attributeSet = null;
    /**
     * 自定义view实现柱状图
     * 首先定义一个类实现View
     */

    //定义画笔
    private Paint mLinePaint;
    private Paint mGreenPaint;
    private Paint mTextPaint;
    //定义上下文
    private Context mContext;
    //定义宽高
    private float weight;
    private float height;
    private float mScale;
    //这个数组是高度的值
    private String[] y_title = {"100", "80", "60", "40", "20", "0"};
    //分别为定义数据与数据源名称的集合
    private static List<Long> mData;
    private static List<String> mNames;

    public PColumn(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        PColumn.context = context;
        attributeSet = attrs;
        //给定义的画笔进行加工
        mContext = context;
        mLinePaint = new Paint();
        mGreenPaint = new Paint();
        mTextPaint = new Paint();

        mLinePaint.setARGB(255, 223, 233, 231);
        mGreenPaint.setARGB(255, 0, 200, 149);
        mTextPaint.setARGB(255, 153, 153, 153);

        mGreenPaint.setStyle(Paint.Style.FILL);

        mTextPaint.setAntiAlias(true);
        mGreenPaint.setAntiAlias(true);
        mLinePaint.setAntiAlias(true);

        mScale = context.getResources().getDisplayMetrics().density;
    }

    //尺寸发生改变的时候调用
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        weight = 0.7F * w;
        height = 0.70F * h;
    }
    //绘制
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        float min_height = height / 5;
        for (int i = 5; i >= 0; i--) {
            if (i == 5) {
                mLinePaint.setARGB(255, 131, 148, 144);
            } else {
                mLinePaint.setARGB(255, 223, 233, 231);
            }
            canvas.drawLine(70 * mScale, 30 * mScale + min_height * i, 70 * mScale + weight, 30 * mScale + min_height * i, mLinePaint);
            mTextPaint.setTextAlign(Paint.Align.RIGHT);
            mTextPaint.setTextSize(10 * mScale);
            canvas.drawText(y_title[i], 60 * mScale, 32 * mScale + min_height * i, mTextPaint);
        }
        float min_weight = (weight - 70 * mScale) / (mData.size());
        mTextPaint.setTextSize(12 * mScale);
        mTextPaint.setTextAlign(Paint.Align.CENTER);
        for (int i = 0; i < mData.size(); i++) {
            int leftR = (int) (70 * mScale + i * min_weight + min_weight / 2);
            int rightR = leftR + (int) (min_weight / 2);
            int buttomR = (int) (30 * mScale + min_height * 5);
            int topR = buttomR - (int) (height / 100 * mData.get(i));
            canvas.drawRect(new RectF(leftR, topR, rightR, buttomR), mGreenPaint);
            mTextPaint.setARGB(255, 153, 153, 153);
            canvas.drawText(mNames.get(i), leftR + min_weight / 4, buttomR + 20 * mScale, mTextPaint);
            mTextPaint.setARGB(255, 51, 51, 51);
            canvas.drawText(mData.get(i) + "", leftR + min_weight / 4, topR - 10 * mScale, mTextPaint);
        }
    }
    //传入数据并进行绘制
    public PColumn(List<Long> data, List<String> name) {
        super(PColumn.context,PColumn.attributeSet);
        mData = data;
        mNames = name;
        invalidate();
    }

}

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private static List<Long> mData;        //  数据值
    private static List<String> mNames;     //  数据姓名


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


        //  柱形图
        initSQLiteTwo();
        PColumn pColumn = new PColumn(mData,mNames);    //  将数据源传递给自定义柱形图类
    }

    private void initSQLiteTwo() {
        //初始化数据
        mData = new ArrayList<>();
        mNames = new ArrayList<>();
        mData = new ArrayList<>();
        mNames = new ArrayList<>();
        
        mData.add((long) 20);       
        mData.add((long) 10);
        mData.add((long) 30);
        mData.add((long) 40);
        mNames.add("停车费");
        mNames.add("过路费");
        mNames.add("油费");
        mNames.add("罚款");
    }
}