用Android实现商品详情页。 要求： 1. 点击某一个商品进入本商品的详情页，详情页数据包括商品图片、商品名称、商品价格、该商品的详细介绍。 2. 商品详情页底部包含一个“购买”按钮，点击购买后，跳转到购物车页面。 3. 购物车页面可实现商品数量的增减、商品的删除以及总价格计算功能。给出详细代码，1.adapter要在新建类中，2.使用listview

好的，以下是实现商品详情页的Android代码：

1. 商品详情页布局文件 detail_layout.xml

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/img_product"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:scaleType="centerCrop" />

    <TextView
        android:id="@+id/tv_product_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="16dp"
        android:textSize="18sp" />

    <TextView
        android:id="@+id/tv_product_price"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="16dp"
        android:textSize="18sp" />

    <TextView
        android:id="@+id/tv_product_desc"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="16dp"
        android:textSize="16sp" />

    <Button
        android:id="@+id/btn_buy"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="购买" />

</LinearLayout>

2. 商品详情页Activity文件 DetailActivity.java

public class DetailActivity extends AppCompatActivity {

    private ImageView imgProduct;
    private TextView tvProductName, tvProductPrice, tvProductDesc;
    private Button btnBuy;

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

        imgProduct = findViewById(R.id.img_product);
        tvProductName = findViewById(R.id.tv_product_name);
        tvProductPrice = findViewById(R.id.tv_product_price);
        tvProductDesc = findViewById(R.id.tv_product_desc);
        btnBuy = findViewById(R.id.btn_buy);

        // 获取商品信息
        Intent intent = getIntent();
        String productName = intent.getStringExtra("productName");
        String productPrice = intent.getStringExtra("productPrice");
        String productDesc = intent.getStringExtra("productDesc");
        int productImage = intent.getIntExtra("productImage", 0);

        // 设置商品信息
        imgProduct.setImageResource(productImage);
        tvProductName.setText(productName);
        tvProductPrice.setText(productPrice);
        tvProductDesc.setText(productDesc);

        // 设置购买按钮点击事件
        btnBuy.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(DetailActivity.this, CartActivity.class);
                startActivity(intent);
            }
        });
    }
}

3. 购物车页面布局文件 cart_layout.xml

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ListView
        android:id="@+id/list_cart"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>

    <TextView
        android:id="@+id/tv_total_price"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="16dp"
        android:textSize="18sp" />

    <Button
        android:id="@+id/btn_checkout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="结算" />

</LinearLayout>

4. 购物车页面Adapter文件 CartAdapter.java

public class CartAdapter extends BaseAdapter {

    private List<Product> productList;
    private Context context;

    public CartAdapter(List<Product> productList, Context context) {
        this.productList = productList;
        this.context = context;
    }

    @Override
    public int getCount() {
        return productList.size();
    }

    @Override
    public Object getItem(int position) {
        return productList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.cart_item, null);
            viewHolder = new ViewHolder();
            viewHolder.imgProduct = convertView.findViewById(R.id.img_product);
            viewHolder.tvProductName = convertView.findViewById(R.id.tv_product_name);
            viewHolder.tvProductPrice = convertView.findViewById(R.id.tv_product_price);
            viewHolder.btnDecrease = convertView.findViewById(R.id.btn_decrease);
            viewHolder.tvProductCount = convertView.findViewById(R.id.tv_product_count);
            viewHolder.btnIncrease = convertView.findViewById(R.id.btn_increase);
            viewHolder.btnDelete = convertView.findViewById(R.id.btn_delete);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        Product product = productList.get(position);

        viewHolder.imgProduct.setImageResource(product.getProductImage());
        viewHolder.tvProductName.setText(product.getProductName());
        viewHolder.tvProductPrice.setText(product.getProductPrice());
        viewHolder.tvProductCount.setText(String.valueOf(product.getProductCount()));

        viewHolder.btnDecrease.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int count = product.getProductCount();
                if (count > 1) {
                    count--;
                    product.setProductCount(count);
                    notifyDataSetChanged();
                }
            }
        });

        viewHolder.btnIncrease.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int count = product.getProductCount();
                count++;
                product.setProductCount(count);
                notifyDataSetChanged();
            }
        });

        viewHolder.btnDelete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                productList.remove(position);
                notifyDataSetChanged();
            }
        });

        return convertView;
    }

    class ViewHolder {
        ImageView imgProduct;
        TextView tvProductName, tvProductPrice, tvProductCount;
        Button btnDecrease, btnIncrease, btnDelete;
    }
}

5. 购物车页面Activity文件 CartActivity.java

public class CartActivity extends AppCompatActivity {

    private ListView listCart;
    private TextView tvTotalPrice;
    private Button btnCheckout;

    private List<Product> productList = new ArrayList<>();
    private CartAdapter cartAdapter;

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

        listCart = findViewById(R.id.list_cart);
        tvTotalPrice = findViewById(R.id.tv_total_price);
        btnCheckout = findViewById(R.id.btn_checkout);

        // 模拟购物车数据
        productList.add(new Product("商品1", "100元", R.drawable.product1, 1));
        productList.add(new Product("商品2", "200元", R.drawable.product2, 1));
        productList.add(new Product("商品3", "300元", R.drawable.product3, 1));
        cartAdapter = new CartAdapter(productList, this);
        listCart.setAdapter(cartAdapter);

        // 计算总价
        double totalPrice = 0;
        for (Product product : productList) {
            totalPrice += Double.parseDouble(product.getProductPrice().replace("元", "")) * product.getProductCount();
        }
        tvTotalPrice.setText("总价：" + totalPrice + "元");

        // 设置结算按钮点击事件
        btnCheckout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(CartActivity.this, "结算成功", Toast.LENGTH_SHORT).show();
            }
        });
    }
}

其中，商品实体类Product.java：

public class Product {

    private String productName;
    private String productPrice;
    private int productImage;
    private int productCount;

    public Product(String productName, String productPrice, int productImage, int productCount) {
        this.productName = productName;
        this.productPrice = productPrice;
        this.productImage = productImage;
        this.productCount = productCount;
    }

    public String getProductName() {
        return productName;
    }

    public void setProductName(String productName) {
        this.productName = productName;
    }

    public String getProductPrice() {
        return productPrice;
    }

    public void setProductPrice(String productPrice) {
        this.productPrice = productPrice;
    }

    public int getProductImage() {
        return productImage;
    }

    public void setProductImage(int productImage) {
        this.productImage = productImage;
    }

    public int getProductCount() {
        return productCount;
    }

    public void setProductCount(int productCount) {
        this.productCount = productCount;
    }
}

以上就是实现商品详情页及购物车功能的Android代码，希望能对你有所帮助。