In this report, we focus on the electromagnetic properties of hadrons which can help us understand the structures of resonances. We review our works about the radiative decays of $D_{s0}^*(2317)$, $D_{s1}^{\prime}(2460)$, and $X(3872)$ where the molecule components play important roles. We discuss the final-state interaction effects in the electron-positron annihilation processes and compare with new experimental data.